scholarly journals Metabotropic glutamate receptors in GtoPdb v.2021.3

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Francine Acher ◽  
Giuseppe Battaglia ◽  
Hans Bräuner-Osborne ◽  
P. Jeffrey Conn ◽  
Robert Duvoisin ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
G Protein ◽  
Metabotropic Glutamate Receptors ◽  
Receptor Subtypes ◽  
Allosteric Modulators ◽  
Group Iii ◽  
Mglu Receptor ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

Metabotropic glutamate (mGlu) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Metabotropic Glutamate Receptors [347]) are a family of G protein-coupled receptors activated by the neurotransmitter glutamate [138]. The mGlu family is composed of eight members (named mGlu1 to mGlu8) which are divided in three groups based on similarities of agonist pharmacology, primary sequence and G protein coupling to effector: Group-I (mGlu1 and mGlu5), Group-II (mGlu2 and mGlu3) and Group-III (mGlu4, mGlu6, mGlu7 and mGlu8) (see Further reading).Structurally, mGlu are composed of three juxtaposed domains: a core G protein-activating seven-transmembrane domain (TM), common to all GPCRs, is linked via a rigid cysteine-rich domain (CRD) to the Venus Flytrap domain (VFTD), a large bi-lobed extracellular domain where glutamate binds. mGlu form constitutive dimers, cross-linked by a disulfide bridge. The structures of the VFTD of mGlu1, mGlu2, mGlu3, mGlu5 and mGlu7 have been solved [198, 271, 264, 399]. The structure of the 7 transmembrane (TM) domains of both mGlu1 and mGlu5 have been solved, and confirm a general helical organization similar to that of other GPCRs, although the helices appear more compacted [87, 429, 61]. Recent advances in cryo-electron microscopy have provided structures of full-length mGlu receptor dimers [189]. Studies have revealed the possible formation of heterodimers between either group-I receptors, or within and between group-II and -III receptors [88]. First well characterized in transfected cells, co-localization and specific pharmacological properties also suggest the existence of such heterodimers in the brain [266].[436, 143, 279]. Beyond heteromerization with other mGlu receptor subtypes, increasing evidence suggests mGlu receptors form heteromers and larger order complexes with class A GPCRs (reviewed in [138]). The endogenous ligands of mGlu are L-glutamic acid, L-serine-O-phosphate, N-acetylaspartylglutamate (NAAG) and L-cysteine sulphinic acid. Group-I mGlu receptors may be activated by 3,5-DHPG and (S)-3HPG [30] and antagonized by (S)-hexylhomoibotenic acid [232]. Group-II mGlu receptors may be activated by LY389795 [265], LY379268 [265], eglumegad [350, 430], DCG-IV and (2R,3R)-APDC [351], and antagonised by eGlu [168] and LY307452 [421, 103]. Group-III mGlu receptors may be activated by L-AP4 and (R,S)-4-PPG [128]. An example of an antagonist selective for mGlu receptors is LY341495, which blocks mGlu2 and mGlu3 at low nanomolar concentrations, mGlu8 at high nanomolar concentrations, and mGlu4, mGlu5, and mGlu7 in the micromolar range [183]. In addition to orthosteric ligands that directly interact with the glutamate recognition site, allosteric modulators that bind within the TM domain have been described. Negative allosteric modulators are listed separately. The positive allosteric modulators most often act as ‘potentiators’ of an orthosteric agonist response, without significantly activating the receptor in the absence of agonist.

scholarly journals Metabotropic glutamate receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Francine Acher ◽  
Giuseppe Battaglia ◽  
Hans Bräuner-Osborne ◽  
P. Jeffrey Conn ◽  
Robert Duvoisin ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
G Protein ◽  
Metabotropic Glutamate Receptors ◽  
Transmembrane Domain ◽  
Acid Group ◽  
Allosteric Modulators ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

Metabotropic glutamate (mGlu) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Metabotropic Glutamate Receptors [334]) are a family of G protein-coupled receptors activated by the neurotransmitter glutamate. The mGlu family is composed of eight members (named mGlu1 to mGlu8) which are divided in three groups based on similarities of agonist pharmacology, primary sequence and G protein coupling to effector: Group-I (mGlu1 and mGlu5), Group-II (mGlu2 and mGlu3) and Group-III (mGlu4, mGlu6, mGlu7 and mGlu8) (see Further reading).Structurally, mGlu are composed of three juxtaposed domains: a core G protein-activating seven-transmembrane domain (TM), common to all GPCRs, is linked via a rigid cysteine-rich domain (CRD) to the Venus Flytrap domain (VFTD), a large bi-lobed extracellular domain where glutamate binds. The structures of the VFTD of mGlu1, mGlu2, mGlu3, mGlu5 and mGlu7 have been solved [190, 262, 255, 386]. The structure of the 7 transmembrane (TM) domains of both mGlu1 and mGlu5 have been solved, and confirm a general helical organization similar to that of other GPCRs, although the helices appear more compacted [85, 415, 59]. mGlu form constitutive dimers crosslinked by a disulfide bridge. Recent studies revealed the possible formation of heterodimers between either group-I receptors, or within and between group-II and -III receptors [86]. Although well characterized in transfected cells, co-localization and specific pharmacological properties also suggest the existence of such heterodimers in the brain [422, 257]. The endogenous ligands of mGlu are L-glutamic acid, L-serine-O-phosphate, N-acetylaspartylglutamate (NAAG) and L-cysteine sulphinic acid. Group-I mGlu receptors may be activated by 3,5-DHPG and (S)-3HPG [29] and antagonized by (S)-hexylhomoibotenic acid [223]. Group-II mGlu receptors may be activated by LY389795 [256], LY379268 [256], eglumegad [337, 416], DCG-IV and (2R,3R)-APDC [338], and antagonised by eGlu [161] and LY307452 [408, 100]. Group-III mGlu receptors may be activated by L-AP4 and (R,S)-4-PPG [125]. An example of an antagonist selective for mGlu receptors is LY341495, which blocks mGlu2 and mGlu3 at low nanomolar concentrations, mGlu8 at high nanomolar concentrations, and mGlu4, mGlu5, and mGlu7 in the micromolar range [176]. In addition to orthosteric ligands that directly interact with the glutamate recognition site, allosteric modulators that bind within the TM domain have been described. Negative allosteric modulators are listed separately. The positive allosteric modulators most often act as ‘potentiators’ of an orthosteric agonist response, without significantly activating the receptor in the absence of agonist.

Groups II and III Metabotropic Glutamate Receptors Differentially Modulate Brief and Prolonged Nociception in Primate STT Cells

2000 ◽  
Vol 84 (6) ◽  
pp. 2998-3009 ◽  
Author(s):  
Volker Neugebauer ◽  
Ping-Sun Chen ◽  
William D. Willis
Keyword(s):  
Glutamate Receptors ◽  
Dorsal Horn ◽  
Central Sensitization ◽  
Metabotropic Glutamate Receptors ◽  
Background Activity ◽  
Mechanical Stimuli ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

The heterogeneous family of G-protein-coupled metabotropic glutamate receptors (mGluRs) provides excitatory and inhibitory controls of synaptic transmission and neuronal excitability in the nervous system. Eight mGluR subtypes have been cloned and are classified in three subgroups. Group I mGluRs can stimulate phosphoinositide hydrolysis and activate protein kinase C whereas group II (mGluR2 and 3) and group III (mGluR4, 6, 7, and 8) mGluRs share the ability to inhibit cAMP formation. The present study examined the roles of groups II and III mGluRs in the processing of brief nociceptive information and capsaicin-induced central sensitization of primate spinothalamic tract (STT) cells in vivo. In 11 anesthetized male monkeys ( Macaca fascicularis), extracellular recordings were made from 21 STT cells in the lumbar dorsal horn. Responses to brief (15 s) cutaneous stimuli of innocuous (brush), marginally and distinctly noxious (press and pinch, respectively) intensity were recorded before, during, and after the infusion of group II and group III mGluR agonists into the dorsal horn by microdialysis. Different concentrations were applied for at least 20 min each (at 5 μl/min) to obtain cumulative concentration-response relationships. Values in this paper refer to the drug concentrations in the microdialysis fibers; actual concentrations in the tissue are about three orders of magnitude lower. The agonists were also applied at 10–25 min after intradermal capsaicin injection. The group II agonists (2S,1′S,2′S)-2-(carboxycyclopropyl)glycine (LCCG1, 1 μM-10 mM, n = 6) and (−)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY379268; 1 μM-10 mM, n = 6) had no significant effects on the responses to brief cutaneous mechanical stimuli (brush, press, pinch) or on ongoing background activity. In contrast, the group III agonist L(+)-2-amino-4-phosphonobutyric acid (LAP4, 0.1 μM-10 mM, n = 6) inhibited the responses to cutaneous mechanical stimuli in a concentration-dependent manner, having a stronger effect on brush responses than on responses to press and pinch. LAP4 did not change background discharges significantly. Intradermal injections of capsaicin increased ongoing background activity and sensitized the STT cells to cutaneous mechanical stimuli (ongoing activity > brush > press > pinch). When given as posttreatment, the group II agonists LCCG1 (100 μM, n = 5) and LY379268 (100 μM, n = 6) and the group III agonist LAP4 (100 μM, n = 6) reversed the capsaicin-induced sensitization. After washout of the agonists, the central sensitization resumed. Our data suggest that, while activation of both group II and group III mGluRs can reverse capsaicin-induced central sensitization, it is the actions of group II mGluRs in particular that undergo significant functional changes during central sensitization because they modulate responses of sensitized STT cells but have no effect under control conditions.

Roles of specific metabotropic glutamate receptor subtypes in regulation of hippocampal CA1 pyramidal cell excitability

1995 ◽  
Vol 74 (1) ◽  
pp. 122-129 ◽  
Author(s):  
R. W. Gereau ◽  
P. J. Conn
Keyword(s):  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate Receptor ◽  
Brain Slices ◽  
Second Messenger ◽  
Receptor Subtypes ◽  
Bhk Cells ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

1. Metabotropic glutamate receptors (mGluRs) are coupled to various second-messenger systems through guanosine 5'-triphosphate-binding proteins. To date, at least seven mGluRs have been cloned, and these mGluR subtypes can be divided into three major groups on the basis of similarities in amino acid sequence, coupling to second-messenger cascades in expression systems, and pharmacological profiles. These groups include group I (mGluR1 and mGluR5), group II (mGluR2 and mGluR3), and group III (mGluR4, mGluR6, and mGluR7). 2. On the basis of its selective activation of phosphoinositide hydrolysis in brain slices and its ability to activate mGluR1a expressed in Xenopus oocytes, others have suggested that 3.5-dihydroxyphenylglycine (DHPG) may be selective for group I mGluRs. Consistent with this hypothesis, we report that DHPG also activates mGluR5 expressed in oocytes, whereas it is inactive at mGluR4 and mGluR7 expressed in baby hamster kidney (BHK) cells. The compound (2S,1'R,2'R,3'R)-2-(2.3-dicarboxycyclopropyl)glycine (DCG-IV) activates both mGluR2 and mGluR3 at submicromolar concentrations, whereas it is inactive at mGluR4 and mGluR1, suggesting that this compound may be selective for group II mGluRs. Consistent with this hypothesis, we find that DCG-IV does not activate mGluR5 expressed in oocytes and does not activate mGluR7 expressed in BHK cells. These findings suggest that DHPG and DCG-IV are highly selective agonists for group I and group II mGluRs, respectively. 3. Previous studies that have examined the physiological roles of mGluRs have generally used agonists that do not differentiate between the various subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Antagonists reversibly reverse chemical LTD induced by group I, group II and group III metabotropic glutamate receptors

2013 ◽  
Vol 74 ◽  
pp. 135-146 ◽  
Author(s):  
David Lodge ◽  
Patrick Tidball ◽  
Marion S. Mercier ◽  
Sarah J. Lucas ◽  
Lydia Hanna ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

Modulation of mEPSCs in Olfactory Bulb Mitral Cells by Metabotropic Glutamate Receptors

1997 ◽  
Vol 78 (3) ◽  
pp. 1468-1475 ◽  
Author(s):  
N. E. Schoppa ◽  
G. L. Westbrook
Keyword(s):  
Olfactory Bulb ◽  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Mitral Cells ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Selective Agonist ◽  
Group I ◽  
Mepsc Frequency ◽  
Group Ii

Schoppa, N. E. and G. L. Westbrook. Modulation of mEPSCs in olfactory bulb mitral cells by metabotropic glutamate receptors. J. Neurophysiol. 78: 1468–1475, 1997. Olfactory bulb mitral cells express group I (mGluR1), group II (mGluR2), and group III (mGluR7 and mGluR8) metabotropic glutamate receptors. We examined the role of these mGluRs on excitatory synaptic transmission in cultured mitral cells with the use of whole cell patch-clamp recordings. The effects of group-selective mGluR agonists and antagonists were tested on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-receptor-mediated miniature excitatory postsynaptic currents (mEPSCs). (1S,3R)-1-amino-cyclopentane-1,3-dicarboxylate (ACPD) or the group-I-selective agonist 3,5-dihydroxyphenylglycine evoked an inward current accompanied by a decrease in membrane conductance, consistent with the previously described closure of potassium channels by group I agonists. The increased cellular excitability was accompanied by an increase in mEPSC frequency in some cells. When calcium entry was blocked by cadmium, ACPD or the group-II-selective agonist 2-(2,3-dicarboxycyclopropyl)-glycine reduced the mEPSC frequency. l-2-amino-4-phosphonobutyric acid (l-AP4), a group-III-selective agonist, caused a similar decrease. The concentration-dependence ofl-AP4-mediated inhibition was most consistent with activation of mGluR8. We investigated two possible effector mechanisms for the group III presynaptic receptor. Bath application of forskolin or 3-isobutyl-1-methylxantine had no effect on mEPSC frequency. Increasing calcium influx by raising extracellular K+ caused a large increase in the mEPSC frequency but did not enhance l-AP4-mediated inhibition. Thus inhibition of mEPSCs involves a mechanism downstream of calcium entry and appears to be independent of adenosine 3′,5′-cyclic monophosphate. Our results indicate that both group II and III receptors can inhibit glutamate release at mitral cell terminals. Although group II/III receptors had a similar effect on mEPSCs, differences in location on nerve terminals and in glutamate sensitivity suggest that each mGluR may have discrete actions on mitral cell activity.

Evidence for Involvement of Group II/III Metabotropic Glutamate Receptors in NMDA Receptor–Independent Long-Term Potentiation in Area CA1 of Rat Hippocampus

1999 ◽  
Vol 82 (6) ◽  
pp. 2956-2969 ◽  
Author(s):  
Lawrence M. Grover ◽  
Chen Yan
Keyword(s):  
Nmda Receptor ◽  
G Protein ◽  
Metabotropic Glutamate Receptors ◽  
Pyramidal Neurons ◽  
Field Potential ◽  
Long Term Potentiation ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

Previous studies implicated metabotropic glutamate receptors (mGluRs) in N-methyl-d-aspartate (NMDA) receptor–independent long-term potentiation (LTP) in area CA1 of the rat hippocampus. To learn more about the specific roles played by mGluRs in NMDA receptor–independent LTP, we used whole cell recordings to load individual CA1 pyramidal neurons with a G-protein inhibitor [guanosine-5′-O-(2-thiodiphosphate), GDPβS]. Although loading postsynaptic CA1 pyramidal neurons with GDPβS significantly reduced G-protein dependent postsynaptic potentials, GDPβS failed to prevent NMDA receptor– independent LTP, suggesting that postsynaptic G-protein–dependent mGluRs are not required. We also performed a series of extracellular field potential experiments in which we applied group-selective mGluR antagonists. We had previously determined that paired-pulse facilitation (PPF) was decreased during the first 30–45 min of NMDA receptor–independent LTP. To determine if mGluRs might be involved in these PPF changes, we used a twin-pulse stimulation protocol to measure PPF in field potential experiments. NMDA receptor–independent LTP was prevented by a group II mGluR antagonist [(2S)-α-ethylglutamic acid] and a group III mGluR antagonist [(RS)-α-cyclopropyl-4-phosphonophenylglycine], but was not prevented by other group II and III mGluR antagonists [(RS)-α-methylserine-O-phosphate monophenyl ester or (RS)-α-methylserine-O-phosphate]. NMDA receptor–independent LTP was not prevented by either of the group I mGluR antagonists we examined, (RS)-1-aminoindan-1,5-dicarboxylic acid and 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester. The PPF changes which accompany NMDA receptor–independent LTP were not prevented by any of the group-selective mGluR antagonists we examined, even when the LTP itself was blocked. Finally, we found that tetanic stimulation in the presence of group III mGluR antagonists lead to nonspecific potentiation in control (nontetanized) input pathways. Taken together, our results argue against the involvement of postsynaptic group I mGluRs in NMDA receptor–independent LTP. Group II and/or group III mGluRs are required, but the specific details of the roles played by these mGluRs in NMDA receptor–independent LTP are uncertain. Based on the pattern of results we obtained, we suggest that group II mGluRs are required for induction of NMDA receptor–independent LTP, and that group III mGluRs are involved in determining the input specificity of NMDA receptor–independent LTP by suppressing potentiation of nearby, nontetanized synapses.

Activation of Metabotropic Glutamate Receptors Modulates the Voltage-Gated Sustained Calcium Current in a Teleost Horizontal Cell

1999 ◽  
Vol 81 (2) ◽  
pp. 425-434 ◽  
Author(s):  
Cindy L. Linn ◽  
Adele C. Gafka
Keyword(s):  
Glutamate Receptors ◽  
Calcium Current ◽  
Metabotropic Glutamate Receptors ◽  
Horizontal Cell ◽  
Horizontal Cells ◽  
Group Iii ◽  
Voltage Gated ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

Activation of metabotropic glutamate receptors modulates the voltage-gated sustained calcium current in a teleost horizontal cell. In the teleost retina, cone horizontal cells contain a voltage-activated sustained calcium current, which has been proposed to be involved in visual processing. Recently, several studies have demonstrated that modulation of voltage-gated channels can occur through activation of metabotropic glutamate receptors (mGluRs). Because glutamate is the excitatory neurotransmitter in the vertebrate retina, we have used whole cell electrophysiological techniques to examine the effect of mGluR activation on the sustained voltage-gated calcium current found in isolated cone horizontal cells in the catfish retina. In pharmacological conditions that blocked voltage-gated sodium and potassium channels, as well as N-methyl-d-aspartate (NMDA) and non-NMDA channels, application of l-glutamate or 1-aminocyclopentane-1,3-dicarboxylic acid (1 S,3 R-ACPD) to voltage-clamped cone horizontal cells acted to increase the amplitude of the calcium current, expand the activation range of the calcium current by 10 mV into the cell’s physiological operating range, and shift the peak calcium current by −5 mV. To identify and characterize the mGluR subtypes found on catfish cone horizontal cells, agonists of group I, group II, or group III mGluRs were applied via perfusion. Group I and group III mGluR agonists mimicked the effect of l-glutamate or 1 S,3 R-ACPD, whereas group II mGluR agonists had no effect on L-type calcium current activity. Inhibition studies demonstrated that group I mGluR antagonists significantly blocked the modulatory effect of the group I mGluR agonist, ( S)-3,5-dihydroxyphenylglycine. Similar results were obtained when the group III mGluR agonist,l-2-amino-4-phosphonobutyric acid, was applied in the presence of a group III mGluR antagonist. These results provide evidence for two groups of mGluR subtypes on catfish cone horizontal cells. Activation of these mGluRs is linked to modulation of the voltage-gated sustained calcium current.

Determining calmodulin binding to metabotropic glutamate receptors with distinct protein-interaction methods

2004 ◽  
Vol 32 (5) ◽  
pp. 868-870 ◽  
Author(s):  
K. Lidwell ◽  
J. Dillon ◽  
A. Sihota ◽  
V. O'Connor ◽  
B. Pilkington
Keyword(s):  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Calmodulin Binding ◽  
Group I ◽  
Group Ii ◽  
Receptor Interacting Proteins ◽  
G Protein Coupled ◽  
Two Hybrid

mGluRs (metabotropic glutamate receptors) are G-protein-coupled receptors that modulate synaptic transmission. The eight mammalian mGluRs form three groups based on sequence and functional similarities: group I (1 and 5), group II (2 and 3) and group III (4, 6–8) mGluRs. In the present study, we used a Y2H (yeast two hybrid) screen to identify proteins that interact with the C-terminal intracellular tail of mGluR3. Prominent among the candidate receptor interacting proteins was calmodulin, a Ca2+ sensor known to bind identifiable sequences in group I and III mGluRs. The Y2H method was used to investigate calmodulin binding to mGluRs but failed to confirm the documented interaction with group III mGluRs. Furthermore, subsequent biochemical analysis showed that calmodulin does not interact with group II mGluRs. This illustrates that certain Ca2+-dependent interactions are not recapitulated in yeast. Moreover, it highlights the necessity for supporting biochemical data to substantiate interactions identified with Y2H methods.

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