1
|
Fabian CB, Jordan ND, Cole RH, Carley LG, Thompson SM, Seney ML, Joffe ME. Parvalbumin interneuron mGlu 5 receptors govern sex differences in prefrontal cortex physiology and binge drinking. Neuropsychopharmacology 2024:10.1038/s41386-024-01889-0. [PMID: 38773314 DOI: 10.1038/s41386-024-01889-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/23/2024]
Abstract
Despite established sex differences in the prevalence and presentation of psychiatric disorders, little is known about the cellular and synaptic mechanisms that guide these differences under basal conditions. The proper function of the prefrontal cortex (PFC) is essential for the top-down regulation of motivated behaviors. The activity of the PFC is tightly controlled by parvalbumin-expressing interneurons (PV-INs), a key subpopulation of fast-spiking GABAergic cells that regulate cortical excitability through direct innervations onto the perisomatic regions of nearby pyramidal cells. Recent rodent studies have identified notable sex differences in PV-IN activity and adaptations to experiences such as binge drinking. Here, we investigated the cellular and molecular mechanisms that underlie sex-specific regulation of PFC PV-IN function. Using whole-cell patch-clamp electrophysiology and selective pharmacology, we report that PV-INs from female mice are more excitable than those from males. Moreover, we find that mGlu1 and mGlu5 metabotropic glutamate receptors regulate cell excitability, excitatory drive, and endocannabinoid signaling at PFC PV-INs in a sex-dependent manner. Genetic deletion of mGlu5 receptors from PV-expressing cells abrogates all sex differences observed in PV-IN membrane and synaptic physiology. Lastly, we report that female, but not male, PV-mGlu5-/- mice exhibit decreased voluntary drinking on an intermittent access schedule, which could be related to changes in ethanol's stimulant properties. Importantly, these studies identify mGlu1 and mGlu5 receptors as candidate signaling molecules involved in sex differences in PV-IN activity and behaviors relevant to alcohol use.
Collapse
Affiliation(s)
- Carly B Fabian
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nilah D Jordan
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rebecca H Cole
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lily G Carley
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shannon M Thompson
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Marianne L Seney
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Max E Joffe
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA.
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
2
|
Fabian CB, Jordan ND, Cole RH, Carley LG, Thompson SM, Seney ML, Joffe ME. Parvalbumin interneuron mGlu 5 receptors govern sex differences in prefrontal cortex physiology and binge drinking. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.20.567903. [PMID: 38045379 PMCID: PMC10690210 DOI: 10.1101/2023.11.20.567903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Despite established sex differences in the prevalence and presentation of psychiatric disorders, little is known about the cellular and synaptic mechanisms that guide these differences under basal conditions. Proper function of the prefrontal cortex (PFC) is essential for the top-down regulation of motivated behaviors. Activity of the PFC is tightly controlled by parvalbumin-expressing interneurons (PV-INs), a key subpopulation of fast-spiking GABAergic cells that regulate cortical excitability through direct innervations onto the perisomatic regions of nearby pyramidal cells. Recent rodent studies have identified notable sex differences in PV-IN activity and adaptations to experiences such as binge drinking. Here, we investigated the cellular and molecular mechanisms that underlie sex-specific regulation of PFC PV-IN function. Using whole-cell patch clamp electrophysiology and selective pharmacology, we report that PV-INs from female mice are more excitable than those from males. Moreover, we find that mGlu1 and mGlu5 metabotropic glutamate receptors regulate cell excitability, excitatory drive, and endocannabinoid signaling at PFC PV-INs in a sex-dependent manner. Genetic deletion of mGlu5 receptors from PV-expressing cells abrogates all sex differences observed in PV-IN membrane and synaptic physiology. Lastly, we report that female, but not male, PV-mGlu5-/- mice exhibit decreased voluntary drinking on an intermittent access schedule, which could be related to changes in ethanol's stimulant properties. Importantly, these studies identify mGlu1 and mGlu5 receptors as candidate signaling molecules involved in sex differences in PV-IN activity and behaviors relevant for alcohol use.
Collapse
Affiliation(s)
- Carly B Fabian
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Nilah D Jordan
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Rebecca H Cole
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Lily G Carley
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Shannon M Thompson
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Marianne L Seney
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| | - Max E Joffe
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
- Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience University of Pittsburgh, Pittsburgh, PA
| |
Collapse
|
3
|
McCullock TW, Kammermeier PJ. The evidence for and consequences of metabotropic glutamate receptor heterodimerization. Neuropharmacology 2021; 199:108801. [PMID: 34547332 DOI: 10.1016/j.neuropharm.2021.108801] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 09/07/2021] [Accepted: 09/17/2021] [Indexed: 12/15/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are an essential component of the mammalian central nervous system. These receptors modulate neuronal excitability in response to extracellular glutamate through the activation of intracellular heterotrimeric G proteins. Like most other class C G protein-coupled receptors, mGluRs function as obligate dimer proteins, meaning they need to form dimer complexes before becoming functional receptors. All mGluRs possess the ability to homodimerize, but studies over the past ten years have demonstrated these receptors are also capable of forming heterodimers in specific patterns. These mGluR heterodimers appear to have their own unique biophysical behavior and pharmacology with both native and synthetic compounds with few rules having been identified that allow for prediction of the consequences of any particular mGluR pair forming heterodimers. Here, we review the relevant literature demonstrating the existence and consequences of mGluR heterodimerization. By collecting biophysical and pharmacological data of several mGluR heterodimers we demonstrate the lack of generalizable behavior of these complexes indicating that each individual dimeric pair needs to be investigated independently. Additionally, by combining sequence alignment and structural analysis, we propose that interactions between the β4-A Helix Loop and the D Helix in the extracellular domain of these receptors are the structural components that dictate heterodimerization compatibility. Finally, we discuss the potential implications of mGluR heterodimerization from the viewpoints of further developing our understanding of neuronal physiology and leveraging mGluRs as a therapeutic target for the treatment of pathophysiology.
Collapse
Affiliation(s)
- Tyler W McCullock
- Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Box 711, Rochester, NY, 14642, USA.
| | - Paul J Kammermeier
- Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Box 711, Rochester, NY, 14642, USA.
| |
Collapse
|
4
|
Targeting metabotropic glutamate receptors for the treatment of depression and other stress-related disorders. Neuropharmacology 2021; 196:108687. [PMID: 34175327 DOI: 10.1016/j.neuropharm.2021.108687] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/11/2021] [Accepted: 06/18/2021] [Indexed: 12/15/2022]
Abstract
The discovery of robust antidepressant effects of ketamine in refractory patients has led to increasing focus on agents targeting glutamatergic signaling as potential novel antidepressant strategy. Among the agents targeting the glutamatergic system, compounds acting at metabotropic glutamate (mGlu) receptors are among the most promising agents under studies for depressive disorders. Further, the receptor diversity, distinct distribution in the CNS, and ability to modulate the glutamatergic neurotransmission in the brain areas implicated in mood disorders make them an exciting target for stress-related disorders. In preclinical models, antidepressant and anxiolytic effects of mGlu5 negative allosteric modulators (NAMs) have been reported. Interestingly, mGlu2/3 receptor antagonists show fast and sustained antidepressant-like effects similar to that of ketamine in rodents. Excitingly, they can also induce antidepressant effects in the animal models of treatment-resistant depression and are devoid of the side-effects associated with ketamine. Unfortunately, clinical trials of both mGlu5 and mGlu2/3 receptor NAMs have been inconclusive, and additional trials using other compounds with suitable preclinical and clinical properties are needed. Although group III mGlu receptors have gained less attention, mGlu7 receptor ligands have been shown to induce antidepressant-like effects in rodents. Collectively, compounds targeting mGlu receptors provide an alternative approach to fill the outstanding clinical need for safer and more efficacious antidepressants. This article is part of the special Issue on "Glutamate Receptors - mGluRs".
Collapse
|
5
|
Defining the Homo- and Heterodimerization Propensities of Metabotropic Glutamate Receptors. Cell Rep 2021; 31:107605. [PMID: 32375054 PMCID: PMC7271767 DOI: 10.1016/j.celrep.2020.107605] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/10/2020] [Accepted: 04/10/2020] [Indexed: 01/02/2023] Open
Abstract
The eight metabotropic glutamate receptors (mGluRs) serve critical modulatory roles throughout the nervous system. The molecular diversity of mGluRs is thought to be further expanded by the formation of heterodimers, but the co-expression of mGluR subtypes at the cellular level and the relative propensities of heterodimer formation are not well known. Here, we analyze single-cell RNA sequencing data and find that cortical pyramidal cells express multiple mGluR subtypes with distinct profiles for different receptor combinations. We then develop quantitative, fluorescence-based assays to define the relative homo- and heterodimer propensities across group-I, -II, and -III mGluRs. We find a strong preference for heterodimerization in a number of cases, including mGluR2 with mGluR3, which we confirm in frontal cortex using in situ RNA hybridization and co-immunoprecipitation. Together, our findings support the biological relevance of mGluR heterodimerization and highlight the complex landscape of mGluR populations in the brain.
Collapse
|
6
|
Thibado JK, Tano JY, Lee J, Salas-Estrada L, Provasi D, Strauss A, Marcelo Lamim Ribeiro J, Xiang G, Broichhagen J, Filizola M, Lohse MJ, Levitz J. Differences in interactions between transmembrane domains tune the activation of metabotropic glutamate receptors. eLife 2021; 10:e67027. [PMID: 33880992 PMCID: PMC8102066 DOI: 10.7554/elife.67027] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/19/2021] [Indexed: 12/16/2022] Open
Abstract
The metabotropic glutamate receptors (mGluRs) form a family of neuromodulatory G-protein-coupled receptors that contain both a seven-helix transmembrane domain (TMD) and a large extracellular ligand-binding domain (LBD) which enables stable dimerization. Although numerous studies have revealed variability across subtypes in the initial activation steps at the level of LBD dimers, an understanding of inter-TMD interaction and rearrangement remains limited. Here, we use a combination of single molecule fluorescence, molecular dynamics, functional assays, and conformational sensors to reveal that distinct TMD assembly properties drive differences between mGluR subtypes. We uncover a variable region within transmembrane helix 4 (TM4) that contributes to homo- and heterodimerization in a subtype-specific manner and tunes orthosteric, allosteric, and basal activation. We also confirm a critical role for a conserved inter-TM6 interface in stabilizing the active state during orthosteric or allosteric activation. Together this study shows that inter-TMD assembly and dynamic rearrangement drive mGluR function with distinct properties between subtypes.
Collapse
Affiliation(s)
- Jordana K Thibado
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical SciencesNew YorkUnited States
| | | | - Joon Lee
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
| | - Leslie Salas-Estrada
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Alexa Strauss
- Tri-Institutional PhD Program in Chemical BiologyNew YorkUnited States
| | | | - Guoqing Xiang
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
| | | | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Martin J Lohse
- Max Delbrück Center for Molecular MedicineBerlinGermany
- ISAR Bioscience InstitutePlanegg-MunichGermany
| | - Joshua Levitz
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical SciencesNew YorkUnited States
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
- Tri-Institutional PhD Program in Chemical BiologyNew YorkUnited States
| |
Collapse
|
7
|
Werthmann RC, Tzouros M, Lamerz J, Augustin A, Fritzius T, Trovò L, Stawarski M, Raveh A, Diener C, Fischer C, Gassmann M, Lindemann L, Bettler B. Symmetric signal transduction and negative allosteric modulation of heterodimeric mGlu1/5 receptors. Neuropharmacology 2020; 190:108426. [PMID: 33279506 DOI: 10.1016/j.neuropharm.2020.108426] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 11/09/2020] [Accepted: 12/01/2020] [Indexed: 10/22/2022]
Abstract
For a long time metabotropic glutamate receptors (mGluRs) were thought to regulate neuronal functions as obligatory homodimers. Recent reports, however, indicate the existence of heterodimers between group-II and -III mGluRs in the brain, which differ from the homodimers in their signal transduction and sensitivity to negative allosteric modulators (NAMs). Whether the group-I mGluRs, mGlu1 and mGlu5, form functional heterodimers in the brain is still a matter of debate. We now show that mGlu1 and mGlu5 co-purify from brain membranes and hippocampal tissue and co-localize in cultured hippocampal neurons. Complementation assays with mutants deficient in agonist-binding or G protein-coupling reveal that mGlu1/5 heterodimers are functional in heterologous cells and transfected cultured hippocampal neurons. In contrast to heterodimers between group-II and -III mGluRs, mGlu1/5 receptors exhibit a symmetric signal transduction, with both protomers activating G proteins to a similar extent. NAMs of either protomer in mGlu1/5 receptors partially inhibit signaling, showing that both protomers need to be able to reach an active conformation for full receptor activity. Complete heterodimer inhibition is observed when both protomers are locked in their inactive state by a NAM. In summary, our data show that mGlu1/5 heterodimers exhibit a symmetric signal transduction and thus intermediate signaling efficacy and kinetic properties. Our data support the existence of mGlu1/5 heterodimers in neurons and highlight differences in the signaling transduction of heterodimeric mGluRs that influence allosteric modulation.
Collapse
Affiliation(s)
- Ruth C Werthmann
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Manuel Tzouros
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Jens Lamerz
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Angélique Augustin
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Thorsten Fritzius
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Luca Trovò
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Michal Stawarski
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Adi Raveh
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Catherine Diener
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Christophe Fischer
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Martin Gassmann
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland
| | - Lothar Lindemann
- Roche Pharmaceutical Research and Early Development, Discovery Neuroscience, Neuroscience and Rare Diseases (NRD) (LL, CD, CF), Pharmaceutical Sciences, Biomarkers, Bioinformatics and Omics & Pathology (MT, JL, AA), Roche Innovation Center Basel, Grenzacherstrasse 124, 4070, Basel, Switzerland.
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland.
| |
Collapse
|
8
|
Mechanisms Underlying Enhancement of Spontaneous Glutamate Release by Group I mGluRs at a Central Auditory Synapse. J Neurosci 2020; 40:7027-7042. [PMID: 32801152 DOI: 10.1523/jneurosci.2771-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 02/06/2023] Open
Abstract
One emerging concept in neuroscience states that synaptic vesicles and the molecular machinery underlying spontaneous transmitter release are different from those underlying action potential-driven synchronized transmitter release. Differential neuromodulation of these two distinct release modes by metabotropic glutamate receptors (mGluRs) constitutes critical supporting evidence. However, the mechanisms underlying such a differential modulation are not understood. Here, we investigated the mechanisms of the modulation by group I mGluRs (mGluR Is) on spontaneous glutamate release in the medial nucleus of the trapezoid body (MNTB), an auditory brainstem nucleus critically involved in sound localization. Whole-cell patch recordings from brainstem slices of mice of both sexes were performed. Activation of mGluR I by 3,5-dihydroxyphenylglycine (3,5-DHPG; 200 μm) produced an inward current at -60 mV and increased spontaneous glutamate release in MNTB neurons. Pharmacological evidence indicated involvement of both mGluR1 and mGluR5, which was further supported for mGluR5 by immunolabeling results. The modulation was eliminated by blocking NaV channels (tetrodotoxin, 1 μm), persistent Na+ current (I NaP; riluzole, 10 μm), or CaV channels (CdCl2, 100 μm). Presynaptic calyx recordings revealed that 3,5-DHPG shifted the activation of I NaP to more hyperpolarized voltages and increased I NaP at resting membrane potential. Our data indicate that mGluR I enhances spontaneous glutamate release via regulation of I NaP and subsequent Ca2+-dependent processes under resting condition.SIGNIFICANCE STATEMENT For brain cells to communicate with each other, neurons release chemical messengers, termed neurotransmitters, in response to action potential invasion (evoked release). Neurons also release neurotransmitters spontaneously. Recent work has revealed different release machineries underlying these two release modes, and their different roles in synaptic development and plasticity. Our recent work discovered differential neuromodulation of these two release modes, but the mechanisms are not well understood. The present study showed that activation of group I metabotropic glutamate receptors enhanced spontaneous glutamate release in an auditory brainstem nucleus, while suppressing evoked release. The modulation is dependent on a persistent Na+ current and involves subsequent Ca2+ signaling, providing insight into the mechanisms underlying the different release modes in auditory processing.
Collapse
|
9
|
Bridi M, Schoch H, Florian C, Poplawski SG, Banerjee A, Hawk JD, Porcari GS, Lejards C, Hahn CG, Giese KP, Havekes R, Spruston N, Abel T. Transcriptional corepressor SIN3A regulates hippocampal synaptic plasticity via Homer1/mGluR5 signaling. JCI Insight 2020; 5:92385. [PMID: 32069266 DOI: 10.1172/jci.insight.92385] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 02/12/2020] [Indexed: 12/12/2022] Open
Abstract
Long-term memory depends on the control of activity-dependent neuronal gene expression, which is regulated by epigenetic modifications. The epigenetic modification of histones is orchestrated by the opposing activities of 2 classes of regulatory complexes: permissive coactivators and silencing corepressors. Much work has focused on coactivator complexes, but little is known about the corepressor complexes that suppress the expression of plasticity-related genes. Here, we define a critical role for the corepressor SIN3A in memory and synaptic plasticity, showing that postnatal neuronal deletion of Sin3a enhances hippocampal long-term potentiation and long-term contextual fear memory. SIN3A regulates the expression of genes encoding proteins in the postsynaptic density. Loss of SIN3A increases expression of the synaptic scaffold Homer1, alters the metabotropic glutamate receptor 1α (mGluR1α) and mGluR5 dependence of long-term potentiation, and increases activation of ERK in the hippocampus after learning. Our studies define a critical role for corepressors in modulating neural plasticity and memory consolidation and reveal that Homer1/mGluR signaling pathways may be central molecular mechanisms for memory enhancement.
Collapse
Affiliation(s)
| | | | | | | | - Anamika Banerjee
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | - Chang-Gyu Hahn
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | - Nelson Spruston
- Howard Hughes Medical Institute (HHMI) Janelia Research Campus, Ashburn, Virginia, USA
| | | |
Collapse
|
10
|
Wu H, Gao S, Terakawa S. Inhibitory effects of fucoidan on NMDA receptors and l-type Ca 2+ channels regulating the Ca 2+ responses in rat neurons. PHARMACEUTICAL BIOLOGY 2019; 57:1-7. [PMID: 30734636 PMCID: PMC6374951 DOI: 10.1080/13880209.2018.1548626] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/19/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
CONTEXT Fucoidan, a sulphated polysaccharide extracted from brown algae [Fucus vesiculosus Linn. (Fucaceae)], has multiple biological activities. OBJECTIVE The effects of fucoidan on Ca2+ responses of rat neurons and its probable mechanisms with focus on glutamate receptors were examined. MATERIALS AND METHODS The neurons isolated from the cortex and hippocampi of Wistar rats in postnatal day 1 were employed. The intracellular Ca2+ responses triggered by various stimuli were measured in vitro by Fura-2/AM. Fucoidan at 0.5 mg/mL or 1.5 mg/mL was applied for 3 min to determine its effects on Ca2+ responses. RT-PCR was used to determine the mRNA expression of neuron receptors treated with fucoidan at 0.5 mg/mL for 3 h. RESULTS The Ca2+ responses induced by NMDA were 100% suppressed by fucoidan, and those induced by Bay K8644 90% in the cortical neurons. However, fucoidan has no significant effect on the Ca2+ responses of cortical neurons induced by AMPA or quisqualate. Meanwhile, the Ca2+ responses of hippocampal neurons induced by glutamate, ACPD or adrenaline, showed only a slight decrease following fucoidan treatment. RT-PCR assays of cortical and hippocampal neurons showed that fucoidan treatment significantly decreased the mRNA expression of NMDA-NR1 receptor and the primer pair for l-type Ca2+ channels, PR1/PR2. DISCUSSION AND CONCLUSIONS Our data indicate that fucoidan suppresses the intracellular Ca2+ responses by selectively inhibiting NMDA receptors in cortical neurons and l-type Ca2+ channels in hippocampal neurons. A wide spectrum of fucoidan binding to cell membrane may be useful for designing a general purpose drug in future.
Collapse
MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/metabolism
- Cells, Cultured
- Cerebellar Cortex/cytology
- Cerebellar Cortex/drug effects
- Excitatory Amino Acid Agonists/pharmacology
- Glutamic Acid/pharmacology
- Hippocampus/cytology
- Hippocampus/drug effects
- N-Methylaspartate/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Polysaccharides/pharmacology
- Rats
- Rats, Wistar
- Receptors, AMPA/metabolism
- Receptors, Glutamate/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/biosynthesis
- Receptors, N-Methyl-D-Aspartate/metabolism
Collapse
Affiliation(s)
- Hong Wu
- Laboratory of Cell Imaging, Henan University of Chinese Medicine, Zhengzhou, China;
- Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shuibo Gao
- Laboratory of Cell Imaging, Henan University of Chinese Medicine, Zhengzhou, China;
| | - Susumu Terakawa
- Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| |
Collapse
|
11
|
Dal Prà I, Armato U, Chiarini A. Family C G-Protein-Coupled Receptors in Alzheimer's Disease and Therapeutic Implications. Front Pharmacol 2019; 10:1282. [PMID: 31719824 PMCID: PMC6826475 DOI: 10.3389/fphar.2019.01282] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD), particularly its sporadic or late-onset form (SAD/LOAD), is the most prevalent (96–98% of cases) neurodegenerative dementia in aged people. AD’s neuropathology hallmarks are intrabrain accumulation of amyloid-β peptides (Aβs) and of hyperphosphorylated Tau (p-Tau) proteins, diffuse neuroinflammation, and progressive death of neurons and oligodendrocytes. Mounting evidences suggest that family C G-protein-coupled receptors (GPCRs), which include γ-aminobutyric acid B receptors (GABABRs), metabotropic glutamate receptors (mGluR1-8), and the calcium-sensing receptor (CaSR), are involved in many neurotransmitter systems that dysfunction in AD. This review updates the available knowledge about the roles of GPCRs, particularly but not exclusively those expressed by brain astrocytes, in SAD/LOAD onset and progression, taking stock of their respective mechanisms of action and of their potential as anti-AD therapeutic targets. In particular, GABABRs prevent Aβs synthesis and neuronal hyperexcitability and group I mGluRs play important pathogenetic roles in transgenic AD-model animals. Moreover, the specific binding of Aβs to the CaSRs of human cortical astrocytes and neurons cultured in vitro engenders a pathological signaling that crucially promotes the surplus synthesis and release of Aβs and hyperphosphorylated Tau proteins, and also of nitric oxide, vascular endothelial growth factor-A, and proinflammatory agents. Concurrently, Aβs•CaSR signaling hinders the release of soluble (s)APP-α peptide, a neurotrophic agent and GABABR1a agonist. Altogether these effects progressively kill human cortical neurons in vitro and likely also in vivo. Several CaSR’s negative allosteric modulators suppress all the noxious effects elicited by Aβs•CaSR signaling in human cortical astrocytes and neurons thus safeguarding neurons’ viability in vitro and raising hopes about their potential therapeutic benefits in AD patients. Further basic and clinical investigations on these hot topics are needed taking always heed that activation of the several brain family C GPCRs may elicit divergent upshots according to the models studied.
Collapse
Affiliation(s)
- Ilaria Dal Prà
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Anna Chiarini
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| |
Collapse
|
12
|
León-Navarro DA, Albasanz JL, Martín M. Functional Cross-Talk between Adenosine and Metabotropic Glutamate Receptors. Curr Neuropharmacol 2019; 17:422-437. [PMID: 29663888 PMCID: PMC6520591 DOI: 10.2174/1570159x16666180416093717] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/19/2018] [Accepted: 04/13/2018] [Indexed: 12/14/2022] Open
Abstract
Abstract: G-protein coupled receptors are transmembrane proteins widely expressed in cells and their transduction pathways are mediated by controlling second messenger levels through different G-protein interactions. Many of these receptors have been described as involved in the physiopathology of neurodegenerative diseases and even considered as potential targets for the design of novel therapeutic strategies. Endogenous and synthetic allosteric and orthosteric selective ligands are able to modulate GPCRs at both gene and protein expression levels and can also modify their physiological function. GPCRs that coexist in the same cells can homo- and heteromerize, therefore, modulating their function. Adenosine receptors are GPCRs which stimulate or inhibit adenylyl cyclase activity through Gi/Gs protein and are involved in the control of neurotransmitter release as glutamate. In turn, metabotropic glutamate receptors are also GPCRs which inhibit adenylyl cyclase or stimulate phospholipase C activities through Gi or Gq proteins, respectively. In recent years, evidence of crosstalk mechanisms be-tween different GPCRs have been described. The aim of the present review was to summarize the described mechanisms of interaction and crosstalking between adenosine and metabotropic glutamate receptors, mainly of group I, in both in vitro and in vivo systems, and their possible use for the design of novel ligands for the treatment of neurodegenerative diseases.
Collapse
Affiliation(s)
- David Agustín León-Navarro
- Departamento de Quimica Inorganica, Organica y Bioquimica. CRIB, Universidad de Castilla-La Mancha, Spain.,Facultad de Ciencias y Tecnologías Químicas, Avenida Camilo José Cela, 10, 13071 Ciudad Real, Spain
| | - José Luis Albasanz
- Departamento de Quimica Inorganica, Organica y Bioquimica. CRIB, Universidad de Castilla-La Mancha, Spain.,Facultad de Ciencias y Tecnologías Químicas, Avenida Camilo José Cela, 10, 13071 Ciudad Real, Spain.,Facultad de Medicina de Ciudad Real, Camino Moledores s/n. 13071 Ciudad Real, Spain
| | - Mairena Martín
- Departamento de Quimica Inorganica, Organica y Bioquimica. CRIB, Universidad de Castilla-La Mancha, Spain.,Facultad de Ciencias y Tecnologías Químicas, Avenida Camilo José Cela, 10, 13071 Ciudad Real, Spain.,Facultad de Medicina de Ciudad Real, Camino Moledores s/n. 13071 Ciudad Real, Spain
| |
Collapse
|
13
|
McCullock TW, Kammermeier PJ. Target validation: Weak selectivity of LY341495 for mGluR2 over mGluR4 makes glutamate a less selective agonist. Pharmacol Res Perspect 2019; 7:e00471. [PMID: 31065376 PMCID: PMC6498410 DOI: 10.1002/prp2.471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 02/23/2019] [Indexed: 12/02/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are class C G protein coupled receptors with widespread expression in the central nervous system. There are eight mGluRs in the mammalian genome. Research on mGluRs relies on the availability of selective compounds. While many selective allosteric compounds have been described, selectivity of orthosteric agonists and antagonists has been more difficult due to the similarity of the glutamate binding pocket across the mGluR family. LY341495 has been used for decades as a potent and selective group II mGluR antagonist. The selectivity of LY341495 was investigated here between mGluR2, a group II mGluR, and mGluR4, a group III receptor, heterologously expressed in adult rat sympathetic neurons from the superior cervical ganglion (SCG), which provides a null-mGluR background upon which mGluRs were examined in isolation. The compound does in fact selectively inhibit mGluR2 over mGluR4, but in such a way that it makes signaling of the two receptors more difficult to distinguish. The glutamate potency of mGluR2 is about 10-fold higher than mGluR4. 50 nmol L-1 LY341495 did not alter mGluR4 signaling but shifted the mGluR2 glutamate dose-response about 10-fold, such that it overlapped more closely with that of mGluR4. Increasing the LY341494 dose to 500 nmol L-1 further shifted the glutamate dose-response of mGluR2 by another ~10-fold, but also shifted that of mGluR4 similarly. Thus, while glutamate is a moderately selective agonist of mGluR2 over mGluR4 when applied alone, in the presence of increasing concentrations of LY341495, this selectivity of glutamate is lost.
Collapse
Affiliation(s)
- Tyler W. McCullock
- Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterNew York
| | - Paul J. Kammermeier
- Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterNew York
| |
Collapse
|
14
|
Sengmany K, Hellyer SD, Albold S, Wang T, Conn PJ, May LT, Christopoulos A, Leach K, Gregory KJ. Kinetic and system bias as drivers of metabotropic glutamate receptor 5 allosteric modulator pharmacology. Neuropharmacology 2019; 149:83-96. [PMID: 30763654 DOI: 10.1016/j.neuropharm.2019.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/18/2019] [Accepted: 02/04/2019] [Indexed: 12/17/2022]
Abstract
Allosteric modulators of the metabotropic glutamate receptor subtype 5 (mGlu5) have been proposed as potential therapies for various CNS disorders. These ligands bind to sites distinct from the orthosteric (or endogenous) ligand, often with improved subtype selectivity and spatio-temporal control over receptor responses. We recently revealed that mGlu5 allosteric agonists and positive allosteric modulators exhibit biased agonism and/or modulation. To establish whether negative allosteric modulators (NAMs) engender similar bias, we rigorously characterized the pharmacology of eight diverse mGlu5 NAMs. Radioligand inhibition binding studies revealed novel modes of interaction with mGlu5 for select NAMs, with biphasic or incomplete inhibition of the radiolabeled NAM, [3H]methoxy-PEPy. We assessed mGlu5-mediated intracellular Ca2+ (iCa2+) mobilization and inositol phosphate (IP1) accumulation in HEK293A cells stably expressing low levels of mGlu5 (HEK293A-rat mGlu5-low) and mouse embryonic cortical neurons. The apparent affinity of acetylenic NAMs, MPEP, MTEP and dipraglurant, was dependent on the signaling pathway measured, agonist used, and cell type (HEK293A-rat mGlu5-low versus mouse cortical neurons). In contrast, the acetylenic partial NAM, M-5MPEP, and structurally distinct NAMs (VU0366248, VU0366058, fenobam), had similar affinity estimates irrespective of the assay or cellular background. Biased modulation was evident for VU0366248 in mouse cortical neurons where it was a NAM for DHPG-mediated iCa2+ mobilization, but neutral with DHPG in IP1 accumulation assays. Overall, this study highlights the inherent complexity in mGlu5 NAM pharmacology that we hypothesize may influence interpretation when translating into preclinical models and beyond in the design and development of novel therapeutics for neuropsychiatric and neurological disorders.
Collapse
Affiliation(s)
- Kathy Sengmany
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Shane D Hellyer
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Sabine Albold
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Taide Wang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Department of Pharmacology, Monash University, Parkville, VIC, Australia.
| |
Collapse
|
15
|
Biased agonism and allosteric modulation of metabotropic glutamate receptor 5. Clin Sci (Lond) 2018; 132:2323-2338. [PMID: 30389826 DOI: 10.1042/cs20180374] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 12/18/2022]
Abstract
Metabotropic glutamate receptors belong to class C G-protein-coupled receptors and consist of eight subtypes that are ubiquitously expressed throughout the central nervous system. In recent years, the metabotropic glutamate receptor subtype 5 (mGlu5) has emerged as a promising target for a broad range of psychiatric and neurological disorders. Drug discovery programs targetting mGlu5 are primarily focused on development of allosteric modulators that interact with sites distinct from the endogenous agonist glutamate. Significant efforts have seen mGlu5 allosteric modulators progress into clinical trials; however, recent failures due to lack of efficacy or adverse effects indicate a need for a better understanding of the functional consequences of mGlu5 allosteric modulation. Biased agonism is an interrelated phenomenon to allosterism, describing how different ligands acting through the same receptor can differentially influence signaling to distinct transducers and pathways. Emerging evidence demonstrates that allosteric modulators can induce biased pharmacology at the level of intrinsic agonism as well as through differential modulation of orthosteric agonist-signaling pathways. Here, we present key considerations in the discovery and development of mGlu5 allosteric modulators and the opportunities and pitfalls offered by biased agonism and modulation.
Collapse
|
16
|
Di Menna L, Joffe ME, Iacovelli L, Orlando R, Lindsley CW, Mairesse J, Gressèns P, Cannella M, Caraci F, Copani A, Bruno V, Battaglia G, Conn PJ, Nicoletti F. Functional partnership between mGlu3 and mGlu5 metabotropic glutamate receptors in the central nervous system. Neuropharmacology 2017; 128:301-313. [PMID: 29079293 DOI: 10.1016/j.neuropharm.2017.10.026] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 10/09/2017] [Accepted: 10/21/2017] [Indexed: 12/19/2022]
Abstract
mGlu5 receptors are involved in mechanisms of activity-dependent synaptic plasticity, and are targeted by drugs developed for the treatment of CNS disorders. We report that mGlu3 receptors, which are traditionally linked to the control of neurotransmitter release, support mGlu5 receptor signaling in neurons and largely contribute to the robust mGlu5 receptor-mediated polyphosphoinositide hydrolysis in the early postnatal life. In cortical pyramidal neurons, mGlu3 receptor activation potentiated mGlu5 receptor-mediated somatic Ca2+ mobilization, and mGlu3 receptor-mediated long-term depression in the prefrontal cortex required the endogenous activation of mGlu5 receptors. The interaction between mGlu3 and mGlu5 receptors was also relevant to mechanisms of neuronal toxicity, with mGlu3 receptors shaping the influence of mGlu5 receptors on excitotoxic neuronal death. These findings shed new light into the complex role played by mGlu receptors in physiology and pathology, and suggest reconsideration of some of the current dogmas in the mGlu receptor field.
Collapse
Affiliation(s)
| | - Max E Joffe
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232-0697, USA
| | - Luisa Iacovelli
- Department of Physiology and Pharmacology, University Sapienza of Roma, 00185 Roma, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, University Sapienza of Roma, 00185 Roma, Italy
| | - Craig W Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232-0697, USA
| | - Jèrome Mairesse
- PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, 1141 Paris, France
| | - Pierre Gressèns
- PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, 1141 Paris, France; Centre for the Developing Brain, Department of Perinatal Health and Imaging, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | | | - Filippo Caraci
- Department of Drug Sciences, University of Catania, 95125 Catania, Italy; I.R.C.C.S. Oasi Maria SS, 94018 Troina, Italy
| | - Agata Copani
- Department of Drug Sciences, University of Catania, 95125 Catania, Italy; Institute of Biostructure and Bioimaging, National Research Council, 95126 Catania, Italy
| | - Valeria Bruno
- I.R.C.C.S. Neuromed, 86077 Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Roma, 00185 Roma, Italy
| | | | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232-0697, USA
| | - Ferdinando Nicoletti
- I.R.C.C.S. Neuromed, 86077 Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Roma, 00185 Roma, Italy.
| |
Collapse
|
17
|
mGluR1 and mGluR5 Synergistically Control Cholinergic Synaptic Transmission in the Thalamic Reticular Nucleus. J Neurosci 2017; 36:7886-96. [PMID: 27466334 DOI: 10.1523/jneurosci.0409-16.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/08/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Acetylcholine (ACh) signaling is involved in a wide range of processes, including arousal, attention, and learning. An increasing number of studies indicate that cholinergic control of these functions is highly deterministic, mediated by synaptic afferents that generate reliable and precise responses in postsynaptic neurons. However, mechanisms that govern plastic changes of cholinergic synaptic strength are poorly understood, even though they are likely critical in shaping the impact of cholinergic inputs on neuronal networks. We have recently shown that in the thalamic reticular nucleus (TRN), synaptic release of ACh generates excitatory-inhibitory biphasic postsynaptic responses, mediated by the activation of α4β2 nicotinic (nAChRs) and M2 muscarinic receptors (mAChRs), respectively. Here, using voltage-clamp recordings from TRN neurons in thalamocortical slices of mice, we demonstrate that the activation of Group I metabotropic glutamate receptors (mGluRs) by ambient or synaptically released glutamate evokes transient increases of nicotinic EPSCs. Additionally, we find that the selective Group I mGluR agonist DHPG [(S)-3,5-dihydroxyphenylglycine] evokes long-term potentiation of nicotinic EPSCs (mGluR-nLTP), dependent on increases in postsynaptic Ca(2+) concentration and the activation of phospholipase C. Both the induction and the maintenance of mGluR-nLTP require synergistic activation of mGluR1 and mGluR5. Together, our results show that postsynaptic Group I mGluRs are critically involved in the regulation of cholinergic synaptic strength on different time scales, suggesting that cholinergic control of local thalamic circuits is highly context-dependent and regulated by the overall levels of glutamatergic afferent activity. SIGNIFICANCE STATEMENT Cholinergic signaling controls information processing and plasticity in neuronal circuits, but the mechanisms underlying the regulation of cholinergic synaptic strength on different time scales are unknown. Here we identify mGluR1 and mGluR5 as key elements in the dynamic regulation of cholinergic synaptic inputs onto neurons of the TRN. Our findings highlight potential mechanisms that regulate cholinergic signaling in the mammalian brain.
Collapse
|
18
|
Bonifacino T, Cattaneo L, Gallia E, Puliti A, Melone M, Provenzano F, Bossi S, Musante I, Usai C, Conti F, Bonanno G, Milanese M. In-vivo effects of knocking-down metabotropic glutamate receptor 5 in the SOD1 G93A mouse model of amyotrophic lateral sclerosis. Neuropharmacology 2017. [PMID: 28645622 DOI: 10.1016/j.neuropharm.2017.06.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder due to loss of upper and lower motor neurons (MNs). The mechanisms of neuronal death are largely unknown, thus prejudicing the successful pharmacological treatment. One major cause for MN degeneration in ALS is represented by glutamate(Glu)-mediated excitotoxicity. We have previously reported that activation of Group I metabotropic Glu receptors (mGluR1 and mGluR5) at glutamatergic spinal cord nerve terminals produces abnormal Glu release in the widely studied SOD1G93A mouse model of ALS. We also demonstrated that halving mGluR1 expression in the SOD1G93A mouse had a positive impact on survival, disease onset, disease progression, and on a number of cellular and biochemical readouts of ALS. We generated here SOD1G93A mice with reduced expression of mGluR5 (SOD1G93AGrm5-/+) by crossing the SOD1G93A mutant mouse with the mGluR5 heterozigous Grm5-/+ mouse. SOD1G93AGrm5-/+ mice showed prolonged survival probability and delayed pathology onset. These effects were associated to enhanced number of preserved MNs, decreased astrocyte and microglia activation, reduced cytosolic free Ca2+ concentration, and regularization of abnormal Glu release in the spinal cord of SOD1G93AGrm5-/+ mice. Unexpectedly, only male SOD1G93AGrm5-/+ mice showed improved motor skills during disease progression vs. SOD1G93A mice, while SOD1G93AGrm5-/+ females did not. These results demonstrate that a lower constitutive level of mGluR5 has a significant positive impact in mice with ALS and support the idea that blocking Group I mGluRs may represent a potentially effective pharmacological approach to the disease.
Collapse
Affiliation(s)
- Tiziana Bonifacino
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy
| | - Luca Cattaneo
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy
| | - Elena Gallia
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy
| | - Aldamaria Puliti
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy; Medical Genetics Unit, Istituto Giannina Gaslini, Via G. Gaslini, 5 - 16147, Genoa, Italy; Centre of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV, 9 - 16132, Genoa, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Via Tronto 10/a - 60126, Torrette di Ancona, Ancona, Italy; Centre for Neurobiology of Aging, INRCA IRCCS, Via S.Margherita, 5 - 60124, Ancona, Italy
| | - Francesca Provenzano
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy
| | - Simone Bossi
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, L.go P. Daneo, 3 - 16132, Genoa, Italy
| | - Ilaria Musante
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, L.go P. Daneo, 3 - 16132, Genoa, Italy
| | - Cesare Usai
- Institute of Biophysics, National Research Council (CNR), Via Darini, 6 - Torre di Francia, 16149, Genoa, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Via Tronto 10/a - 60126, Torrette di Ancona, Ancona, Italy; Centre for Neurobiology of Aging, INRCA IRCCS, Via S.Margherita, 5 - 60124, Ancona, Italy
| | - Giambattista Bonanno
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy; Centre of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV, 9 - 16132, Genoa, Italy.
| | - Marco Milanese
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa Viale Cembrano, 4 - 16148, Genoa, Italy; Centre of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV, 9 - 16132, Genoa, Italy
| |
Collapse
|
19
|
Leach K, Gregory KJ. Molecular insights into allosteric modulation of Class C G protein-coupled receptors. Pharmacol Res 2017; 116:105-118. [DOI: 10.1016/j.phrs.2016.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 11/18/2016] [Accepted: 12/07/2016] [Indexed: 12/23/2022]
|
20
|
Pandya NJ, Klaassen RV, van der Schors RC, Slotman JA, Houtsmuller A, Smit AB, Li KW. Group 1 metabotropic glutamate receptors 1 and 5 form a protein complex in mouse hippocampus and cortex. Proteomics 2016; 16:2698-2705. [PMID: 27392515 PMCID: PMC5129514 DOI: 10.1002/pmic.201500400] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 06/03/2016] [Accepted: 07/05/2016] [Indexed: 12/31/2022]
Abstract
The group 1 metabotropic glutamate receptors 1 and 5 (mGluR1/5) have been implicated in mechanisms of synaptic plasticity and may serve as potential therapeutic targets in autism spectrum disorders. The interactome of group 1 mGluRs has remained largely unresolved. Using a knockout‐controlled interaction proteomics strategy we examined the mGluR5 protein complex in two brain regions, hippocampus and cortex, and identified mGluR1 as its major interactor in addition to the well described Homer proteins. We confirmed the presence of mGluR1/5 complex by (i) reverse immunoprecipitation using an mGluR1 antibody to pulldown mGluR5 from hippocampal tissue, (ii) coexpression in HEK293 cells followed by coimmunoprecipitation to reveal the direct interaction of mGluR1 and 5, and (iii) superresolution microscopy imaging of hippocampal primary neurons to show colocalization of the mGluR1/5 in the synapse.
Collapse
Affiliation(s)
- Nikhil J Pandya
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands
| | - Remco V Klaassen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands
| | - Roel C van der Schors
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands
| | - Johan A Slotman
- Optical Imaging Center, Erasmus Medical Center, Rotterdam, the Netherlands
| | | | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands
| | - Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands.
| |
Collapse
|
21
|
Peralta F, Fuentealba C, Fiedler J, Aliaga E. Prenatal valproate treatment produces autistic-like behavior and increases metabotropic glutamate receptor 1A-immunoreactivity in the hippocampus of juvenile rats. Mol Med Rep 2016; 14:2807-14. [DOI: 10.3892/mmr.2016.5529] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/13/2016] [Indexed: 11/06/2022] Open
|
22
|
Biased allosteric agonism and modulation of metabotropic glutamate receptor 5: Implications for optimizing preclinical neuroscience drug discovery. Neuropharmacology 2016; 115:60-72. [PMID: 27392634 DOI: 10.1016/j.neuropharm.2016.07.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/30/2016] [Accepted: 07/01/2016] [Indexed: 12/20/2022]
Abstract
Allosteric modulators, that exhibit no intrinsic agonist activity, offer the advantage of spatial and temporal fine-tuning of endogenous agonist activity, allowing the potential for increased selectivity, reduced adverse effects and improved clinical outcomes. Some allosteric ligands can differentially activate and/or modulate distinct signaling pathways arising from the same receptor, phenomena referred to as 'biased agonism' and 'biased modulation'. Emerging evidence for CNS disorders with glutamatergic dysfunction suggests the metabotropic glutamate receptor subtype 5 (mGlu5) is a promising target. Current mGlu5 allosteric modulators have largely been classified based on modulation of intracellular calcium (iCa2+) responses to orthosteric agonists alone. We assessed eight mGlu5 allosteric modulators previously classified as mGlu5 PAMs or PAM-agonists representing four distinct chemotypes across multiple measures of receptor activity, to explore their potential for engendering biased agonism and/or modulation. Relative to the reference orthosteric agonist, DHPG, the eight allosteric ligands exhibited distinct biased agonism fingerprints for iCa2+ mobilization, IP1 accumulation and ERK1/2 phosphorylation in HEK293A cells stably expressing mGlu5 and in cortical neuron cultures. VU0424465, DPFE and VU0409551 displayed the most disparate biased signaling fingerprints in both HEK293A cells and cortical neurons that may account for the marked differences observed previously for these ligands in vivo. Select mGlu5 allosteric ligands also showed 'probe dependence' with respect to their cooperativity with different orthosteric agonists, as well as biased modulation for the magnitude of positive cooperativity observed. Unappreciated biased agonism and modulation may contribute to unanticipated effects (both therapeutic and adverse) when translating from recombinant systems to preclinical models. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
Collapse
|
23
|
Chang K, Roche KW. Structural and molecular determinants regulating mGluR5 surface expression. Neuropharmacology 2016; 115:10-19. [PMID: 27211252 DOI: 10.1016/j.neuropharm.2016.04.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/29/2016] [Accepted: 04/26/2016] [Indexed: 01/29/2023]
Abstract
Trafficking of G protein-coupled receptors (GPCRs) to the plasma membrane is a pivotal process to fulfill their biological functions. Metabotropic glutamate receptors (mGluRs; mGluR1-8) are expressed throughout the CNS and are important for modulating synaptic transmission and plasticity. Group I mGluRs, including mGluR1 and mGluR5, have long intracellular C-terminal tails containing multiple protein binding domains and sites for phosphorylation and ER retention. We have now investigated some of the structural determinants for mGluR5 trafficking to the plasma membrane by studying a series of truncations and ligand binding mutants. We also take advantage of dimer formation between the extracellular domain (ECD) of mGluR5 and design an ECD based surface-binding assay to evaluate dimerization and surface expression of mGluR5 containing various truncations or point mutations. We found that the C terminus is not essential for mGluR5 surface expression. In contrast, the 7th transmembrane domain (TM7) plays a critical role in its surface expression in both heterologous cells and neurons. Furthermore, a ligand binding mutation within the ECD of mGluR5 (Y64A/T174A) that blocks ligand binding impairs both surface expression and dimerization of mGluR5 in neurons. The integrity of both the whole 7TM domain and the C- terminal tail of mGluR5 are also important for stabilizing dimerization with the ECD. Thus multiple domains regulate dimerization and trafficking of mGluR5. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
Collapse
Affiliation(s)
- Kai Chang
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 35, Room 2C903, Bethesda, MD 20892, USA
| | - Katherine W Roche
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 35, Room 2C903, Bethesda, MD 20892, USA.
| |
Collapse
|
24
|
Litim N, Morissette M, Di Paolo T. Metabotropic glutamate receptors as therapeutic targets in Parkinson's disease: An update from the last 5 years of research. Neuropharmacology 2016; 115:166-179. [PMID: 27055772 DOI: 10.1016/j.neuropharm.2016.03.036] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 12/21/2022]
Abstract
Disturbance of glutamate neurotransmission in Parkinson's disease (PD) and l-DOPA induced dyskinesia (LID) is well documented. This review focuses on advances during the past five years on pharmacological modulation of metabotropic glutamate (mGlu) receptors in relation to anti-parkinsonian activity, LID attenuation, and neuroprotection. Drug design and characterization have led to the development of orthosteric agonists binding the same site as glutamate and Positive and Negative Allosteric modulators (PAMs and NAMs) binding sites different from the orthosteric site and offering subtype selectivity. Inhibition of group I (mGlu1 and mGlu5) receptors with NAMs and activation of group II (mGlu2 and 3 receptors) and group III (mGlu 4, 7 and 8 receptors) with PAMs and orthosteric agonists have shown their potential to inhibit glutamate release and attenuate excitotoxicity. Earlier and recent studies have led to the development of mGlu5 receptors NAMs to reduce LID and for neuroprotection, mGlu3 receptor agonists for neuroprotection while mGlu4 receptor PAMs and agonists for antiparkinsonian effects and neuroprotection. Furthermore, homo- and heterodimers of mGlu receptors are documented and highlight the complexity of the functioning of these receptors. Research on partial allosteric modulators and biased mGlu receptor allosteric modulators offer new glutamatergic drugs with better therapeutic effects and less off target adverse activity. Thus these various mGlu receptor targets will enable the development of novel drugs with improved clinical effects for normalization of glutamate transmission, treat PD and LID relief. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
Collapse
Affiliation(s)
- Nadhir Litim
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada; Faculty of Pharmacy, Laval University, Quebec City, Canada
| | - Marc Morissette
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada
| | - Thérèse Di Paolo
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada; Faculty of Pharmacy, Laval University, Quebec City, Canada.
| |
Collapse
|
25
|
Sengmany K, Gregory KJ. Metabotropic glutamate receptor subtype 5: molecular pharmacology, allosteric modulation and stimulus bias. Br J Pharmacol 2015; 173:3001-17. [PMID: 26276909 DOI: 10.1111/bph.13281] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 06/30/2015] [Accepted: 07/26/2015] [Indexed: 12/12/2022] Open
Abstract
The metabotropic glutamate receptor subtype 5 (mGlu5 ) is a family C GPCR that has been implicated in various neuronal processes and, consequently, in several CNS disorders. Over the past few decades, GPCR-based drug discovery, including that for mGlu5 receptors, has turned considerable attention to targeting allosteric binding sites. Modulation of endogenous agonists by allosteric ligands offers the advantages of spatial and temporal fine-tuning of receptor activity, increased selectivity and reduced adverse effects with the potential to elicit improved clinical outcomes. Further, with greater appreciation of the multifaceted nature of the transduction of mGlu5 receptor signalling, it is increasingly apparent that drug discovery must take into consideration unique receptor conformations and the potential for stimulus-bias. This novel paradigm proposes that different ligands may differentially modulate distinct signalling pathways arising from the same receptor. We review our current understanding of the complexities of mGlu5 receptor signalling and regulation, and how these relate to allosteric ligands. Ultimately, a deeper appreciation of these relationships will provide the foundation for targeted drug design of compounds with increased selectivity, not only for the desired receptor but also for the desired signalling outcome from the receptor. Linked Articles This article is part of a themed section on Molecular Pharmacology of G Protein-Coupled Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.20/issuetoc.
Collapse
Affiliation(s)
- K Sengmany
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, Australia
| | - K J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, Australia.
| |
Collapse
|
26
|
Wierońska JM, Zorn SH, Doller D, Pilc A. Metabotropic glutamate receptors as targets for new antipsychotic drugs: Historical perspective and critical comparative assessment. Pharmacol Ther 2015; 157:10-27. [PMID: 26549541 DOI: 10.1016/j.pharmthera.2015.10.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this review, we aim to present, discuss and clarify our current understanding regarding the prediction of possible antipsychotic effects of metabotropic glutamate (mGlu) receptor ligands. The number of preclinical trials clearly indicates, that this group of compounds constitutes an excellent alternative to presently used antipsychotic therapy, being effective not only to positive, but also negative and cognitive symptoms of schizophrenia. Although the results of clinical trials that were performed for the group of mGlu2/3 agonists were not so enthusiastic as in animal studies, they still showed that mGlu ligands do not induced variety of side effects typical for presently used antipsychotics, and were generally well tolerated. The lack of satisfactory effectiveness towards schizophrenia symptoms of mGlu2/3 activators in humans could be a result of variety of uncontrolled factors and unidentified biomarkers different for each schizophrenia patient, that should be taken into consideration in the future set of clinical trials. The subject is still open for further research, and the novel classes of mGlu5 or mGlu2/3 agonists/PAMs were recently introduced, including the large group of compounds from the third group of mGlu receptors, especially of mGlu4 subtype. Finally, more precise treatment based on simultaneous administration of minimal doses of the ligands for two or more receptors, seems to be promising in the context of symptoms-specific schizophrenia treatment.
Collapse
Affiliation(s)
- Joanna M Wierońska
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Poland
| | | | | | - Andrzej Pilc
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Poland.
| |
Collapse
|
27
|
Gregory KJ, Conn PJ. Molecular Insights into Metabotropic Glutamate Receptor Allosteric Modulation. Mol Pharmacol 2015; 88:188-202. [PMID: 25808929 DOI: 10.1124/mol.114.097220] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/24/2015] [Indexed: 12/21/2022] Open
Abstract
The metabotropic glutamate (mGlu) receptors are a group of eight family C G protein-coupled receptors that are expressed throughout the central nervous system (CNS) and periphery. Within the CNS the different subtypes are found in neurons, both pre- and/or postsynaptically, where they mediate modulatory roles and in glial cells. The mGlu receptor family provides attractive targets for numerous psychiatric and neurologic disorders, with the majority of discovery programs focused on targeting allosteric sites, with allosteric ligands now available for all mGlu receptor subtypes. However, the development of allosteric ligands remains challenging. Biased modulation, probe dependence, and molecular switches all contribute to the complex molecular pharmacology exhibited by mGlu receptor allosteric ligands. In recent years we have made significant progress in our understanding of this molecular complexity coupled with an increased understanding of the structural basis of mGlu allosteric modulation.
Collapse
Affiliation(s)
- Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.); and Vanderbilt Center for Neuroscience Drug Discovery & Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (P.J.C)
| | - P Jeffrey Conn
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.); and Vanderbilt Center for Neuroscience Drug Discovery & Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (P.J.C)
| |
Collapse
|