1
|
Lei X, Hofmann CS, Rodriguez AL, Niswender CM. Differential Activity of Orthosteric Agonists and Allosteric Modulators at Metabotropic Glutamate Receptor 7. Mol Pharmacol 2023; 104:17-27. [PMID: 37105671 PMCID: PMC10289241 DOI: 10.1124/molpharm.123.000678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/29/2023] Open
Abstract
Metabotropic glutamate receptor 7 (mGlu7) is a G protein coupled receptor that has demonstrated promise as a therapeutic target across a number of neurologic and psychiatric diseases. Compounds that modulate the activity of mGlu7, such as positive and negative allosteric modulators, may represent new therapeutic strategies to modulate receptor activity. The endogenous neurotransmitter associated with the mGlu receptor family, glutamate, exhibits low efficacy and potency in activating mGlu7, and surrogate agonists, such as the compound L-(+)-2-Amino-4-phosphonobutyric acid (L-AP4), are often used for receptor activation and compound profiling. To understand the implications of the use of such agonists in the development of positive allosteric modulators (PAMs), we performed a systematic evaluation of receptor activation using a system in which mutations can be made in either protomer of the mGlu7 dimer; we employed mutations that prevent interaction with the orthosteric site as well as the G-protein coupling site of the receptor. We then measured increases in calcium levels downstream of a promiscuous G protein to assess the effects of mutations in one of the two protomers in the presence of two different agonists and three positive allosteric modulators. Our results reveal that distinct PAMs, for example N-[3-Chloro-4-[(5-chloro-2-pyridinyl)oxy]phenyl]-2-pyridinecarboxamide (VU0422288) and 3-(2,3-Difluoro-4-methoxyphenyl)-2,5-dimethyl-7-(trifluoromethyl)pyrazolo[1,5-a]pyrimidine (VU6005649), do exhibit different maximal levels of potentiation with L-AP4 versus glutamate, but there appear to be common stable receptor conformations that are shared among all of the compounds examined here. SIGNIFICANCE STATEMENT: This manuscript describes the systematic evaluation of the mGlu7 agonists glutamate and L-(+)-2-Amino-4-phosphonobutyric acid (L-AP4) in the presence and absence of three distinct potentiators examining possible mechanistic differences. These findings demonstrate that mGlu7 potentiators display subtle variances in response to glutamate versus L-AP4.
Collapse
Affiliation(s)
- Xia Lei
- Department of Pharmacology (X.L., C.S.H., A.L.R., C.M.N.), Warren Center for Neuroscience Drug Discovery (X.L., A.L.R., C.M.N.), Vanderbilt Institute of Chemical Biology (C.M.N.), and Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennesee (C.M.N.); and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
| | - Christopher S Hofmann
- Department of Pharmacology (X.L., C.S.H., A.L.R., C.M.N.), Warren Center for Neuroscience Drug Discovery (X.L., A.L.R., C.M.N.), Vanderbilt Institute of Chemical Biology (C.M.N.), and Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennesee (C.M.N.); and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
| | - Alice L Rodriguez
- Department of Pharmacology (X.L., C.S.H., A.L.R., C.M.N.), Warren Center for Neuroscience Drug Discovery (X.L., A.L.R., C.M.N.), Vanderbilt Institute of Chemical Biology (C.M.N.), and Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennesee (C.M.N.); and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
| | - Colleen M Niswender
- Department of Pharmacology (X.L., C.S.H., A.L.R., C.M.N.), Warren Center for Neuroscience Drug Discovery (X.L., A.L.R., C.M.N.), Vanderbilt Institute of Chemical Biology (C.M.N.), and Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennesee (C.M.N.); and Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee (C.M.N.)
| |
Collapse
|
2
|
Lin X, Fisher NM, Dogra S, Senter RK, Reed CW, Kalbfleisch JJ, Lindsley CW, Asher WB, Xiang Z, Niswender CM, Javitch JA. Differential activity of mGlu 7 allosteric modulators provides evidence for mGlu 7/8 heterodimers at hippocampal Schaffer collateral-CA1 synapses. J Biol Chem 2022; 298:102458. [PMID: 36063995 PMCID: PMC9531177 DOI: 10.1016/j.jbc.2022.102458] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/25/2022] Open
Abstract
Glutamate acts at eight metabotropic glutamate (mGlu) receptor subtypes expressed in a partially overlapping fashion in distinct brain circuits. Recent evidence indicates that specific mGlu receptor protomers can heterodimerize and that these heterodimers can exhibit different pharmacology when compared to their homodimeric counterparts. Group III mGlu agonist-induced suppression of evoked excitatory potentials and induction of long-term potentiation at Schaffer collateral-CA1 (SC-CA1) synapses in the rodent hippocampus can be blocked by the selective mGlu7 negative allosteric modulator (NAM), ADX71743. Curiously, a different mGlu7 NAM, 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazonolo[4,5-c]pyridin-4(5H)-one, failed to block these responses in brain slices despite its robust activity at mGlu7 homodimers in vitro. We hypothesized that this might result from heterodimerization of mGlu7 with another mGlu receptor protomer and focused on mGlu8 as a candidate given the reported effects of mGlu8-targeted compounds in the hippocampus. Here, we used complemented donor acceptor-resonance energy transfer to study mGlu7/8 heterodimer activation in vitro and observed that ADX71743 blocked responses of both mGlu7/7 homodimers and mGlu7/8 heterodimers, whereas 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazonolo[4,5-c]pyridin-4(5H)-one only antagonized responses of mGlu7/7 homodimers. Taken together with our electrophysiology observations, these results suggest that a receptor with pharmacology consistent with an mGlu7/8 heterodimer modulates the activity of SC-CA1 synapses. Building on this hypothesis, we identified two additional structurally related mGlu7 NAMs that also differ in their activity at mGlu7/8 heterodimers, in a manner consistent with their ability to inhibit synaptic transmission and plasticity at SC-CA1. Thus, we propose that mGlu7/8 heterodimers are a key molecular target for modulating the activity of hippocampal SC-CA1 synapses.
Collapse
Affiliation(s)
- Xin Lin
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA
| | - Nicole M Fisher
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Shalini Dogra
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Rebecca K Senter
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Carson W Reed
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Jacob J Kalbfleisch
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Wesley B Asher
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA
| | - Zixiu Xiang
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
| | - Jonathan A Javitch
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA; Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA.
| |
Collapse
|