1
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Lao-Peregrin C, Xiang G, Kim J, Srivastava I, Fall AB, Gerhard DM, Kohtala P, Kim D, Song M, Garcia-Marcos M, Levitz J, Lee FS. Synaptic plasticity via receptor tyrosine kinase/G-protein-coupled receptor crosstalk. Cell Rep 2024; 43:113595. [PMID: 38117654 PMCID: PMC10844890 DOI: 10.1016/j.celrep.2023.113595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/15/2023] [Accepted: 12/01/2023] [Indexed: 12/22/2023] Open
Abstract
Cellular signaling involves a large repertoire of membrane receptors operating in overlapping spatiotemporal regimes and targeting many common intracellular effectors. However, both the molecular mechanisms and the physiological roles of crosstalk between receptors, especially those from different superfamilies, are poorly understood. We find that the receptor tyrosine kinase (RTK) TrkB and the G-protein-coupled receptor (GPCR) metabotropic glutamate receptor 5 (mGluR5) together mediate hippocampal synaptic plasticity in response to brain-derived neurotrophic factor (BDNF). Activated TrkB enhances constitutive mGluR5 activity to initiate a mode switch that drives BDNF-dependent sustained, oscillatory Ca2+ signaling and enhanced MAP kinase activation. This crosstalk is mediated, in part, by synergy between Gβγ, released by TrkB, and Gαq-GTP, released by mGluR5, to enable physiologically relevant RTK/GPCR crosstalk.
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Affiliation(s)
| | - Guoqing Xiang
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Jihye Kim
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Ipsit Srivastava
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Alexandra B Fall
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Danielle M Gerhard
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Piia Kohtala
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Daegeon Kim
- Department of Life Sciences, Yeongnam University, Gyeongsan, Gyeongbuk 38451, South Korea
| | - Minseok Song
- Department of Life Sciences, Yeongnam University, Gyeongsan, Gyeongbuk 38451, South Korea
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Joshua Levitz
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Francis S Lee
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA.
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2
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Lao-Peregrin C, Xiang G, Kim J, Srivastava I, Fall AB, Gerhard DM, Kohtala P, Kim D, Song M, Garcia-Marcos M, Levitz J, Lee FS. Synaptic plasticity via receptor tyrosine kinase/G protein-coupled receptor crosstalk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555210. [PMID: 37693535 PMCID: PMC10491144 DOI: 10.1101/2023.08.28.555210] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Cellular signaling involves a large repertoire of membrane receptors operating in overlapping spatiotemporal regimes and targeting many common intracellular effectors. However, both the molecular mechanisms and physiological roles of crosstalk between receptors, especially those from different superfamilies, are poorly understood. We find that the receptor tyrosine kinase (RTK), TrkB, and the G protein-coupled receptor (GPCR), metabotropic glutamate receptor 5 (mGluR5), together mediate a novel form of hippocampal synaptic plasticity in response to brain-derived neurotrophic factor (BDNF). Activated TrkB enhances constitutive mGluR5 activity to initiate a mode-switch that drives BDNF-dependent sustained, oscillatory Ca 2+ signaling and enhanced MAP kinase activation. This crosstalk is mediated, in part, by synergy between Gβγ, released by TrkB, and Gα q -GTP, released by mGluR5, to enable a previously unidentified form of physiologically relevant RTK/GPCR crosstalk.
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3
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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.
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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.)
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4
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Nishiyama K, Nishimura A, Shimoda K, Tanaka T, Kato Y, Shibata T, Tanaka H, Kurose H, Azuma YT, Ihara H, Kumagai Y, Akaike T, Eaton P, Uchida K, Nishida M. Redox-dependent internalization of the purinergic P2Y 6 receptor limits colitis progression. Sci Signal 2022; 15:eabj0644. [PMID: 35015570 DOI: 10.1126/scisignal.abj0644] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Kazuhiro Nishiyama
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Akiyuki Nishimura
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), NINS, Okazaki 444-8787, Japan
| | - Kakeru Shimoda
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), NINS, Okazaki 444-8787, Japan.,Department of Physiological Sciences, SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
| | - Tomohiro Tanaka
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), NINS, Okazaki 444-8787, Japan.,Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
| | - Yuri Kato
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Takahiro Shibata
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Hiroshi Tanaka
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, 2-12-1-H-101, Ookayama, Meguro, Tokyo 152-8552, Japan
| | - Hitoshi Kurose
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasu-Taka Azuma
- Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka 598-8531, Japan
| | - Hideshi Ihara
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, Osaka 599-8531, Japan
| | - Yoshito Kumagai
- Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Takaaki Akaike
- Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
| | - Philip Eaton
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Koji Uchida
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Motohiro Nishida
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.,National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), NINS, Okazaki 444-8787, Japan.,Department of Physiological Sciences, SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan.,Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
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5
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Yamasaki T, Okada M, Hiraishi A, Mori W, Zhang Y, Fujinaga M, Wakizaka H, Kurihara Y, Nengaki N, Zhang MR. Upregulation of Striatal Metabotropic Glutamate Receptor Subtype 1 (mGluR1) in Rats with Excessive Glutamate Release Induced by N-Acetylcysteine. Neurotox Res 2022; 40:26-35. [PMID: 34981453 DOI: 10.1007/s12640-021-00449-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 10/15/2021] [Accepted: 11/16/2021] [Indexed: 10/19/2022]
Abstract
The aim of this study is to investigate the changes in expression of metabotropic glutamate (Glu) receptor subtype 1 (mGluR1), a key molecule involved in neuroexcitetoxicity, during excessive Glu release in the brain by PET imaging. An animal model of excessive Glu release in the brain was produced by intraperitoneally implanting an Alzet osmotic pump containing N-acetylcysteine (NAC), an activator of the cysteine/Glu antiporter, into the abdomen of rats. Basal Glu concentration in the brain was measured by microdialysis, which showed that basal Glu concentration in NAC-treated rats (0.31 µM) was higher than that in saline-treated rats (0.17 µM) at day 7 after the implantation of the osmotic pump. Similarly, PET studies with [11C]ITDM, a useful radioligand for mGluR1 imaging exhibited that the striatal binding potential (BPND) of [11C]ITDM for mGluR1 in PET assessments was increased in NAC-treated animals at day 7 after implantation (2.30) compared with before implantation (1.92). The dynamic changes in striatal BPND during the experimental period were highly correlated with basal Glu concentration. In conclusion, density of mGluR1 is rapidly upregulated by increases in basal Glu concentration, suggesting that mGluR1 might to be a potential biomarker of abnormal conditions in the brain.
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Affiliation(s)
- Tomoteru Yamasaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
| | - Maki Okada
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Atsuto Hiraishi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Wakana Mori
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Yiding Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Masayuki Fujinaga
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Hidekatsu Wakizaka
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Yusuke Kurihara
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.,SHI Accelerator Service Co. Ltd, 1-17-6 Osaki, Shinagawa-ku, Tokyo, 141-0032, Japan
| | - Nobuki Nengaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.,SHI Accelerator Service Co. Ltd, 1-17-6 Osaki, Shinagawa-ku, Tokyo, 141-0032, Japan
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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6
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Structures of human mGlu2 and mGlu7 homo- and heterodimers. Nature 2021; 594:589-593. [PMID: 34135509 DOI: 10.1038/s41586-021-03641-w] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 05/13/2021] [Indexed: 12/16/2022]
Abstract
The metabotropic glutamate receptors (mGlus) are involved in the modulation of synaptic transmission and neuronal excitability in the central nervous system1. These receptors probably exist as both homo- and heterodimers that have unique pharmacological and functional properties2-4. Here we report four cryo-electron microscopy structures of the human mGlu subtypes mGlu2 and mGlu7, including inactive mGlu2 and mGlu7 homodimers; mGlu2 homodimer bound to an agonist and a positive allosteric modulator; and inactive mGlu2-mGlu7 heterodimer. We observed a subtype-dependent dimerization mode for these mGlus, as a unique dimer interface that is mediated by helix IV (and that is important for limiting receptor activity) exists only in the inactive mGlu2 structure. The structures provide molecular details of the inter- and intra-subunit conformational changes that are required for receptor activation, which distinguish class C G-protein-coupled receptors from those in classes A and B. Furthermore, our structure and functional studies of the mGlu2-mGlu7 heterodimer suggest that the mGlu7 subunit has a dominant role in controlling dimeric association and G-protein activation in the heterodimer. These insights into mGlu homo- and heterodimers highlight the complex landscape of mGlu dimerization and activation.
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7
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Lin S, Han S, Cai X, Tan Q, Zhou K, Wang D, Wang X, Du J, Yi C, Chu X, Dai A, Zhou Y, Chen Y, Zhou Y, Liu H, Liu J, Yang D, Wang MW, Zhao Q, Wu B. Structures of G i-bound metabotropic glutamate receptors mGlu2 and mGlu4. Nature 2021; 594:583-588. [PMID: 34135510 DOI: 10.1038/s41586-021-03495-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 03/25/2021] [Indexed: 01/15/2023]
Abstract
The metabotropic glutamate receptors (mGlus) have key roles in modulating cell excitability and synaptic transmission in response to glutamate (the main excitatory neurotransmitter in the central nervous system)1. It has previously been suggested that only one receptor subunit within an mGlu homodimer is responsible for coupling to G protein during receptor activation2. However, the molecular mechanism that underlies the asymmetric signalling of mGlus remains unknown. Here we report two cryo-electron microscopy structures of human mGlu2 and mGlu4 bound to heterotrimeric Gi protein. The structures reveal a G-protein-binding site formed by three intracellular loops and helices III and IV that is distinct from the corresponding binding site in all of the other G-protein-coupled receptor (GPCR) structures. Furthermore, we observed an asymmetric dimer interface of the transmembrane domain of the receptor in the two mGlu-Gi structures. We confirmed that the asymmetric dimerization is crucial for receptor activation, which was supported by functional data; this dimerization may provide a molecular basis for the asymmetric signal transduction of mGlus. These findings offer insights into receptor signalling of class C GPCRs.
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Affiliation(s)
- Shuling Lin
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Shuo Han
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoqing Cai
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qiuxiang Tan
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Kexiu Zhou
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Dejian Wang
- University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xinwei Wang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Juan Du
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Cuiying Yi
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xiaojing Chu
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Antao Dai
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yan Zhou
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yan Chen
- School of Pharmacy, Fudan University, Shanghai, China
| | - Yu Zhou
- University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Hong Liu
- University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jianfeng Liu
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Dehua Yang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ming-Wei Wang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,University of Chinese Academy of Sciences, Beijing, China. .,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, China. .,School of Pharmacy, Fudan University, Shanghai, China. .,School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Qiang Zhao
- University of Chinese Academy of Sciences, Beijing, China. .,State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,Zhongshan Branch, Institute of Drug Discovery and Development, Chinese Academy of Sciences, Zhongshan, China.
| | - Beili Wu
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,University of Chinese Academy of Sciences, Beijing, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, China. .,School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
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8
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Abreu N, Acosta-Ruiz A, Xiang G, Levitz J. Mechanisms of differential desensitization of metabotropic glutamate receptors. Cell Rep 2021; 35:109050. [PMID: 33910009 PMCID: PMC9750234 DOI: 10.1016/j.celrep.2021.109050] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/04/2021] [Accepted: 04/07/2021] [Indexed: 12/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) interact with intracellular transducers to control both signal initiation and desensitization, but the distinct mechanisms that control the regulation of different GPCR subtypes are unclear. Here we use fluorescence imaging and electrophysiology to examine the metabotropic glutamate receptor (mGluR) family. We find distinct properties across subtypes in both rapid desensitization and internalization, with striking differences between the group II mGluRs. mGluR3, but not mGluR2, undergoes glutamate-dependent rapid desensitization, internalization, trafficking, and recycling. We map differences between mGluRs to variable Ser/Thr-rich sequences in the C-terminal domain (CTD) that control interaction with both GPCR kinases and β-arrestins. Finally, we identify a cancer-associated mutation, G848E, within the mGluR3 CTD that enhances β-arrestin coupling and internalization, enabling an analysis of mGluR3 β-arrestin-coupling properties and revealing biased variants. Together, this work provides a framework for understanding the distinct regulation and functional roles of mGluR subtypes.
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Affiliation(s)
- Nohely Abreu
- Biochemistry, Cell and Molecular Biology Graduate Program, Weill Cornell Medicine, New York, NY, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
| | - Amanda Acosta-Ruiz
- Biochemistry, Cell and Molecular Biology Graduate Program, Weill Cornell Medicine, New York, NY, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
| | - Guoqing Xiang
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
| | - Joshua Levitz
- Biochemistry, Cell and Molecular Biology Graduate Program, Weill Cornell Medicine, New York, NY, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA.
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9
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Gregory KJ, Goudet C. International Union of Basic and Clinical Pharmacology. CXI. Pharmacology, Signaling, and Physiology of Metabotropic Glutamate Receptors. Pharmacol Rev 2020; 73:521-569. [PMID: 33361406 DOI: 10.1124/pr.119.019133] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors respond to glutamate, the major excitatory neurotransmitter in the mammalian brain, mediating a modulatory role that is critical for higher-order brain functions such as learning and memory. Since the first mGlu receptor was cloned in 1992, eight subtypes have been identified along with many isoforms and splice variants. The mGlu receptors are transmembrane-spanning proteins belonging to the class C G protein-coupled receptor family and represent attractive targets for a multitude of central nervous system disorders. Concerted drug discovery efforts over the past three decades have yielded a wealth of pharmacological tools including subtype-selective agents that competitively block or mimic the actions of glutamate or act allosterically via distinct sites to enhance or inhibit receptor activity. Herein, we review the physiologic and pathophysiological roles for individual mGlu receptor subtypes including the pleiotropic nature of intracellular signal transduction arising from each. We provide a comprehensive analysis of the in vitro and in vivo pharmacological properties of prototypical and commercially available orthosteric agonists and antagonists as well as allosteric modulators, including ligands that have entered clinical trials. Finally, we highlight emerging areas of research that hold promise to facilitate rational design of highly selective mGlu receptor-targeting therapeutics in the future. SIGNIFICANCE STATEMENT: The metabotropic glutamate receptors are attractive therapeutic targets for a range of psychiatric and neurological disorders. Over the past three decades, intense discovery efforts have yielded diverse pharmacological tools acting either competitively or allosterically, which have enabled dissection of fundamental biological process modulated by metabotropic glutamate receptors and established proof of concept for many therapeutic indications. We review metabotropic glutamate receptor molecular pharmacology and highlight emerging areas that are offering new avenues to selectively modulate neurotransmission.
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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 Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
| | - Cyril Goudet
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
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10
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Metabotropic glutamate receptor 1 is associated with unfavorable prognosis in ER-negative and triple-negative breast cancer. Sci Rep 2020; 10:22292. [PMID: 33339858 PMCID: PMC7749122 DOI: 10.1038/s41598-020-79248-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/01/2020] [Indexed: 01/16/2023] Open
Abstract
New therapies are an urgent medical need in all breast cancer subgroups. Metabotropic glutamate receptor 1 (mGluR1) is suggested as a potential new molecular target. We examined the prevalence mGluR1 expression in different clinically relevant breast cancer subgroups and determined its association with prognosis. In this retrospective cohort, 394 consecutive primary breast cancer tissues were incorporated into a tissue microarray and immunohistochemically stained for mGluR1. The prevalence of mGluR1 protein expression in different breast cancer subgroups was evaluated and correlated with metastasis-free survival (MFS) and overall survival (OS). In total, 56% (n = 219) breast cancer tissues had mGluR1 expression. In estrogen receptor (ER)-negative tumors, 31% (n = 18/58) had mGluR1 expression that was significantly associated with MFS (HR 5.00, 95% CI 1.03–24.35, p = 0.046) in multivariate analysis, independently from other prognostic factors. Of the 44 triple-negative breast cancer (TNBC), 25% (n = 11) expressed mGluR1. mGluR1 expression in TNBC was significantly associated with shorter MFS (HR 8.60, 95% CI 1.06–20.39, p = 0.044) and with poor OS (HR 16.07, 95% CI 1.16–223.10, p = 0.039). In conclusion, mGluR1 is frequently expressed in breast cancer. In ER-negative breast cancer and in TNBC mGluR1 protein expression is an unfavorable prognostic marker. This study provides rationale to explore mGluR1 as a novel target for breast cancer treatment, especially for the more aggressive TNBC.
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11
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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.
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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.
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12
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Lans I, Díaz Ó, Dalton JAR, Giraldo J. Exploring the Activation Mechanism of the mGlu5 Transmembrane Domain. Front Mol Biosci 2020; 7:38. [PMID: 32211419 PMCID: PMC7069277 DOI: 10.3389/fmolb.2020.00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/18/2020] [Indexed: 01/14/2023] Open
Abstract
As a class C GPCR and regulator of synaptic activity, mGlu5 is an attractive drug target, potentially offering treatment for several neurologic and psychiatric disorders. As little is known about the activation mechanism of mGlu5 at a structural level, potential of mean force calculations linked to molecular dynamics simulations were performed on the mGlu5 transmembrane domain crystal structure to explore various internal mechanisms responsible for its activation. Our results suggest that the hydrophilic interactions between intracellular loop 1 and the intracellular side of TM6 have to be disrupted to reach a theoretically active-like conformation. In addition, interactions between residues that are key for mGlu5 activation (Tyr6593.44 and Ile7515.51) and mGlu5 inactivation (Tyr6593.44 and Ser8097.39) have been identified. Inasmuch as mGlu5 receptor signaling is poorly understood, potentially showing a complex network of micro-switches and subtle structure-activity relationships, the present study represents a step forward in the understanding of mGlu5 transmembrane domain activation.
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Affiliation(s)
- Isaias Lans
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia, Medellín, Colombia
| | - Óscar Díaz
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
| | - James A R Dalton
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
| | - Jesús Giraldo
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
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13
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Bertoglio D, Verhaeghe J, Korat Š, Miranda A, Cybulska K, Wyffels L, Stroobants S, Mrzljak L, Dominguez C, Skinbjerg M, Liu L, Munoz-Sanjuan I, Staelens S. Elevated Type 1 Metabotropic Glutamate Receptor Availability in a Mouse Model of Huntington's Disease: a Longitudinal PET Study. Mol Neurobiol 2020; 57:2038-2047. [PMID: 31912442 PMCID: PMC7118044 DOI: 10.1007/s12035-019-01866-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 12/22/2019] [Indexed: 12/11/2022]
Abstract
Impairment of group I metabotropic glutamate receptors (mGluRs) results in altered glutamate signalling, which is associated with several neurological disorders including Huntington’s Disease (HD), an autosomal neurodegenerative disease. In this study, we assessed in vivo pathological changes in mGluR1 availability in the Q175DN mouse model of HD using longitudinal positron emission tomography (PET) imaging with the radioligand [11C]ITDM. Ninety-minute dynamic PET imaging scans were performed in 22 heterozygous (HET) Q175DN mice and 22 wild-type (WT) littermates longitudinally at 6, 12, and 16 months of age. Analyses of regional volume of distribution with an image-derived input function (VT (IDIF)) and voxel-wise parametric VT (IDIF) maps were performed to assess differences between genotypes. Post-mortem evaluation at 16 months was done to support in vivo findings. [11C]ITDM VT (IDIF) quantification revealed higher mGluR1 availability in the brain of HET mice compared to WT littermates (e.g. cerebellum: + 15.0%, + 17.9%, and + 17.6% at 6, 12, and 16 months, respectively; p < 0.001). In addition, an age-related decline in [11C]ITDM binding independent of genotype was observed between 6 and 12 months. Voxel-wise analysis of parametric maps and post-mortem quantifications confirmed the elevated mGluR1 availability in HET mice compared to WT littermates. In conclusion, in vivo measurement of mGluR1 availability using longitudinal [11C]ITDM PET imaging demonstrated higher [11C]ITDM binding in extra-striatal brain regions during the course of disease in the Q175DN mouse model.
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Affiliation(s)
- Daniele Bertoglio
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Špela Korat
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
- Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Alan Miranda
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Klaudia Cybulska
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
- Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
- Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
- Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | | | | | | | - Longbin Liu
- CHDI Management/CHDI Foundation, Los Angeles, CA, USA
| | | | - Steven Staelens
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium.
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14
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Habrian CH, Levitz J, Vyklicky V, Fu Z, Hoagland A, McCort-Tranchepain I, Acher F, Isacoff EY. Conformational pathway provides unique sensitivity to a synaptic mGluR. Nat Commun 2019; 10:5572. [PMID: 31804469 PMCID: PMC6895203 DOI: 10.1038/s41467-019-13407-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/05/2019] [Indexed: 01/07/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are dimeric G-protein-coupled receptors that operate at synapses. Macroscopic and single molecule FRET to monitor structural rearrangements in the ligand binding domain (LBD) of the mGluR7/7 homodimer revealed it to have an apparent affinity ~4000-fold lower than other mGluRs and a maximal activation of only ~10%, seemingly too low for activation at synapses. However, mGluR7 heterodimerizes, and we find it to associate with mGluR2 in the hippocampus. Strikingly, the mGluR2/7 heterodimer has high affinity and efficacy. mGluR2/7 shows cooperativity in which an unliganded subunit greatly enhances activation by agonist bound to its heteromeric partner, and a unique conformational pathway to activation, in which mGluR2/7 partially activates in the Apo state, even when its LBDs are held open by antagonist. High sensitivity and an unusually broad dynamic range should enable mGluR2/7 to respond to both glutamate transients from nearby release and spillover from distant synapses.
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Affiliation(s)
- Chris H Habrian
- Biophysics Graduate Group, University of California, Berkeley, CA, 94720, USA
| | - Joshua Levitz
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10024, USA
| | - Vojtech Vyklicky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Zhu Fu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Adam Hoagland
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | | | | | - Ehud Y Isacoff
- Biophysics Graduate Group, University of California, Berkeley, CA, 94720, USA.
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA.
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA.
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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15
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Mozumder S, Bej A, Srinivasan K, Mukherjee S, Sengupta J. Comprehensive structural modeling and preparation of human 5-HT 2A G-protein coupled receptor in functionally active form. Biopolymers 2019; 111:e23329. [PMID: 31469412 DOI: 10.1002/bip.23329] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 08/07/2019] [Accepted: 08/13/2019] [Indexed: 11/11/2022]
Abstract
The serotonin 2A receptor (5-HT2A R) is an important member of the G-protein coupled receptor (GPCR) family involved in an array of neuromodulatory functions. Although the high-resolution structures of truncated versions of GPCRs, captured in ligand-bound conformational states, are available, the structures lack several functional regions, which have crucial roles in receptor response. Here, in order to understand the structure and dynamics of the ligand-free form of the receptor, we have performed meticulous modeling of the 5-HT2A R with the third intracellular loop (ICL3). Our analyses revealed that the ligand-free ground state structure of 5-HT2A R has marked distinction with ligand-bound conformations of 5-HT2 subfamily proteins and exhibits extensive backbone flexibility across the loop regions, suggesting the importance of purifying the receptor in its native form for further studies. Hence, we have standardized a strategy that efficiently increases the expression of 5-HT2A R by infecting Sf9 cells with a very low multiplicity of infection of baculovirus in conjunction with production boost additive and subsequently, purify the full-length receptor. Furthermore, we have optimized the selective over-expression of glycosylated and nonglycosylated forms of the receptor merely by switching the postinfection growth time, a method that has not been reported earlier.
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Affiliation(s)
- Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Aritra Bej
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Krishnamoorthi Srinivasan
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sujoy Mukherjee
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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16
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Lee S, Park S, Lee H, Han S, Song JM, Han D, Suh YH. Nedd4 E3 ligase and beta-arrestins regulate ubiquitination, trafficking, and stability of the mGlu7 receptor. eLife 2019; 8:44502. [PMID: 31373553 PMCID: PMC6690720 DOI: 10.7554/elife.44502] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 08/01/2019] [Indexed: 12/23/2022] Open
Abstract
The metabotropic glutamate receptor 7 (mGlu7) is a class C G protein-coupled receptor that modulates excitatory neurotransmitter release at the presynaptic active zone. Although post-translational modification of cellular proteins with ubiquitin is a key molecular mechanism governing protein degradation and function, mGlu7 ubiquitination and its functional consequences have not been elucidated yet. Here, we report that Nedd4 ubiquitin E3 ligase and β-arrestins regulate ubiquitination of mGlu7 in heterologous cells and rat neurons. Upon agonist stimulation, β-arrestins recruit Nedd4 to mGlu7 and facilitate Nedd4-mediated ubiquitination of mGlu7. Nedd4 and β-arrestins regulate constitutive and agonist-induced endocytosis of mGlu7 and are required for mGlu7-dependent MAPK signaling in neurons. In addition, Nedd4-mediated ubiquitination results in the degradation of mGlu7 by both the ubiquitin-proteasome system and the lysosomal degradation pathway. These findings provide a model in which Nedd4 and β-arrestin act together as a complex to regulate mGlu7 surface expression and function at presynaptic terminals.
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Affiliation(s)
- Sanghyeon Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Sunha Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyojin Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Seulki Han
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae-Man Song
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Dohyun Han
- Proteomics Core Facility, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Young Ho Suh
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
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17
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Hajj M, De Vita T, Vol C, Renassia C, Bologna JC, Brabet I, Cazade M, Pastore M, Blahos J, Labesse G, Pin JP, Prézeau L. Nonclassical Ligand-Independent Regulation of Go Protein by an Orphan Class C G-Protein–Coupled Receptor. Mol Pharmacol 2019; 96:233-246. [DOI: 10.1124/mol.118.113019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 05/28/2019] [Indexed: 01/20/2023] Open
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18
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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.
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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.
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19
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Suh YH, Chang K, Roche KW. Metabotropic glutamate receptor trafficking. Mol Cell Neurosci 2018; 91:10-24. [PMID: 29604330 DOI: 10.1016/j.mcn.2018.03.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/07/2018] [Accepted: 03/26/2018] [Indexed: 01/14/2023] Open
Abstract
The metabotropic glutamate receptors (mGlu receptors) are G protein-coupled receptors that bind to the excitatory neurotransmitter glutamate and are important in the modulation of neuronal excitability, synaptic transmission, and plasticity in the central nervous system. Trafficking of mGlu receptors in and out of the synaptic plasma membrane is a fundamental mechanism modulating excitatory synaptic function through regulation of receptor abundance, desensitization, and signaling profiles. In this review, we cover the regulatory mechanisms determining surface expression and endocytosis of mGlu receptors, with particular focus on post-translational modifications and receptor-protein interactions. The literature we review broadens our insight into the precise events defining the expression of functional mGlu receptors at synapses, and will likely contribute to the successful development of novel therapeutic targets for a variety of developmental, neurological, and psychiatric disorders.
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Affiliation(s)
- Young Ho Suh
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, South Korea.
| | - Kai Chang
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Katherine W Roche
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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20
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In Vivo Monitoring for Regional Changes of Metabotropic Glutamate Receptor Subtype 1 (mGluR1) in Pilocarpine-Induced Epileptic Rat Brain by Small-Animal PET. Sci Rep 2017; 7:14945. [PMID: 29097780 PMCID: PMC5668420 DOI: 10.1038/s41598-017-15015-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/19/2017] [Indexed: 11/24/2022] Open
Abstract
Metabotropic glutamate receptor subtype 1 (mGluR1) is a crucial pharmacological target for several central nervous system disorders. In this study, we aimed to monitor in vivo regional changes of mGluR1 related to neuroinflammation in the brains of rats after pilocarpine-induced status epilepticus (PISE) using longitudinal positron emission tomography (PET). PISE was induced in rats by administering lithium chloride, followed by repeated pilocarpine hydrochloride treatments. PET assessments were conducted using N-[4-[6-(isopropylamino)-pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methyl-4-[11C]methylbenzamide ([11C]ITDM), a selective radioligand for mGluR1, and N-benzyl-N-[11C]methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide ([11C]DAC), a selective translocator protein PET ligand for neuroinflammation monitoring. PET scans were conducted on PISE rats at 1 day (acute), 1 week (subacute) and 3 weeks (chronic) after repeated seizures. PET with [11C]ITDM showed significant decreases of mGluR1 availability (BPND) in the thalamus and hippocampus after PISE over the chronic period. Conversely, PET with [11C]DAC exhibited a significant increase of radioactive uptake in the forebrain after the acute period, especially in the thalamus. These conflicting changes in the thalamus indicated negative correlation. In conclusion, PET with [11C]ITDM could successfully visualize hippocampal and thalamic declines of mGluR1 related to neuroinflammation, which would help further understanding for mGluR1 functions in neuroexcitotoxicity.
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Investigating the molecular mechanism of positive and negative allosteric modulators in the calcium-sensing receptor dimer. Sci Rep 2017; 7:46355. [PMID: 28417952 PMCID: PMC5394417 DOI: 10.1038/srep46355] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/20/2017] [Indexed: 11/09/2022] Open
Abstract
Allosteric modulators that are targeting the calcium-sensing receptor (CaSR) hold great therapeutic potential, and elucidating the molecular basis for modulation would thus benefit the development of novel therapeutics. In the present study, we aimed at investigating the mechanism of allosteric modulation in CaSR by testing dimers carrying mutations in the allosteric site of one or both of the subunits. To ensure measurements on a well-defined dimer composition, we applied a trans-activation system in which only the specific heterodimer of two loss-of-function mutants responded to agonist. Although one of these mutants was potentiated by a positive allosteric modulator, we showed that receptor activity was further potentiated in a trans-activation heterodimer containing a single allosteric site, however only when the allosteric site was located in the subunit responsible for G protein coupling. On the contrary, preventing activation in both subunits was necessary for obtaining full inhibition by a negative allosteric modulator. These findings correlate with the proposed activation mechanism of the metabotropic glutamate receptors (mGluRs), in which only a single transmembrane domain is activated at a time. CaSR and mGluRs belong to the class C G protein-coupled receptors, and our findings thus suggest that the activation mechanism is common to this subfamily.
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Sergin I, Jong YJI, Harmon SK, Kumar V, O'Malley KL. Sequences within the C Terminus of the Metabotropic Glutamate Receptor 5 (mGluR5) Are Responsible for Inner Nuclear Membrane Localization. J Biol Chem 2017; 292:3637-3655. [PMID: 28096465 DOI: 10.1074/jbc.m116.757724] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 01/12/2017] [Indexed: 12/19/2022] Open
Abstract
Traditionally, G-protein-coupled receptors (GPCR) are thought to be located on the cell surface where they transmit extracellular signals to the cytoplasm. However, recent studies indicate that some GPCRs are also localized to various subcellular compartments such as the nucleus where they appear required for various biological functions. For example, the metabotropic glutamate receptor 5 (mGluR5) is concentrated at the inner nuclear membrane (INM) where it mediates Ca2+ changes in the nucleoplasm by coupling with Gq/11 Here, we identified a region within the C-terminal domain (amino acids 852-876) that is necessary and sufficient for INM localization of the receptor. Because these sequences do not correspond to known nuclear localization signal motifs, they represent a new motif for INM trafficking. mGluR5 is also trafficked to the plasma membrane where it undergoes re-cycling/degradation in a separate receptor pool, one that does not interact with the nuclear mGluR5 pool. Finally, our data suggest that once at the INM, mGluR5 is stably retained via interactions with chromatin. Thus, mGluR5 is perfectly positioned to regulate nucleoplasmic Ca2+in situ.
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Affiliation(s)
- Ismail Sergin
- From the Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Yuh-Jiin I Jong
- From the Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Steven K Harmon
- From the Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Vikas Kumar
- From the Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Karen L O'Malley
- From the Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110
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Mechanism of Assembly and Cooperativity of Homomeric and Heteromeric Metabotropic Glutamate Receptors. Neuron 2016; 92:143-159. [PMID: 27641494 DOI: 10.1016/j.neuron.2016.08.036] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/19/2016] [Accepted: 08/19/2016] [Indexed: 11/23/2022]
Abstract
G protein-coupled receptors (GPCRs) mediate cellular responses to a wide variety of extracellular stimuli. GPCR dimerization may expand signaling diversity and tune functionality, but little is known about the mechanisms of subunit assembly and interaction or the signaling properties of heteromers. Using single-molecule subunit counting on class C metabotropic glutamate receptors (mGluRs), we map dimerization determinants and define a heterodimerization profile. Intersubunit fluorescence resonance energy transfer measurements reveal that interactions between ligand-binding domains control the conformational rearrangements underlying receptor activation. Selective liganding with photoswitchable tethered agonists conjugated to one or both subunits of covalently linked mGluR2 homodimers reveals that receptor activation is highly cooperative. Strikingly, this cooperativity is asymmetric in mGluR2/mGluR3 heterodimers. Our results lead to a model of cooperative activation of mGluRs that provides a framework for understanding how class C GPCRs couple extracellular binding to dimer reorganization and G protein activation.
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Dynamic Changes in Striatal mGluR1 But Not mGluR5 during Pathological Progression of Parkinson's Disease in Human Alpha-Synuclein A53T Transgenic Rats: A Multi-PET Imaging Study. J Neurosci 2016; 36:375-84. [PMID: 26758830 DOI: 10.1523/jneurosci.2289-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Parkinson's disease (PD) is a prevalent degenerative disorder affecting the CNS that is primarily characterized by resting tremor and movement deficits. Group I metabotropic glutamate receptor subtypes 1 and 5 (mGluR1 and mGluR5, respectively) are important targets for investigation in several CNS disorders. In the present study, we investigated the in vivo roles of mGluR1 and mGluR5 in chronic PD pathology by performing longitudinal positron emission tomography (PET) imaging in A53T transgenic (A53T-Tg) rats expressing an abnormal human α-synuclein (ASN) gene. A53T-Tg rats showed a dramatic decline in general motor activities with age, along with abnormal ASN aggregation and striatal neuron degeneration. In longitudinal PET imaging, striatal nondisplaceable binding potential (BPND) values for [(11)C]ITDM (N-[4-[6-(isopropylamino) pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methyl-4-[(11)C]methylbenzamide), a selective PET ligand for mGluR1, temporarily increased before PD symptom onset and dramatically decreased afterward with age. However, striatal BPND values for (E)-[(11)C]ABP688 [3-(6-methylpyridin-2-ylethynyl)-cyclohex-2-enone-(E)-O-[(11)C]methyloxime], a specific PET ligand for mGluR5, remained constant during experimental terms. The dynamic changes in striatal mGluR1 BPND values also showed a high correlation in pathological decreases in general motor activities. Furthermore, declines in mGluR1 BPND values were correlated with decreases in BPND values for [(18)F]FE-PE2I [(E)-N-(3-iodoprop-2E-enyl)-2β-carbo-[(18)F]fluoroethoxy-3β-(4-methylphenyl) nortropane], a specific PET ligand for the dopamine transporter, a biomarker for dopaminergic neurons. In conclusion, our results have demonstrated for the first time that dynamic changes occur in mGluR1, but not mGluR5, that accompany pathological progression in a PD animal model. SIGNIFICANCE STATEMENT Synaptic signaling by glutamate, the principal excitatory neurotransmitter in the brain, is modulated by group I metabotropic glutamate receptors, including the mGluR1 and mGluR5 subtypes. In the brain, mGluR1 and mGluR5 have distinct functional roles and regional distributions. Their roles in brain pathology, however, are not well characterized. Using longitudinal PET imaging in a chronic rat model of PD, we demonstrated that expression of mGluR1, but not mGluR5, dynamically changed in the striatum accompanying pathological PD progression. These findings imply that monitoring mGluR1 in vivo may provide beneficial information to further understand central nervous system disorders.
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Shimoda Y, Yamasaki T, Fujinaga M, Ogawa M, Kurihara Y, Nengaki N, Kumata K, Yui J, Hatori A, Xie L, Zhang Y, Kawamura K, Zhang MR. Synthesis and Evaluation of Novel Radioligands Based on 3-[5-(Pyridin-2-yl)-2H-tetrazol-2-yl]benzonitrile for Positron Emission Tomography Imaging of Metabotropic Glutamate Receptor Subtype 5. J Med Chem 2016; 59:3980-90. [DOI: 10.1021/acs.jmedchem.6b00209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Yoko Shimoda
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Tomoteru Yamasaki
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Masayuki Fujinaga
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Masanao Ogawa
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
- SHI Accelerator
Service Co. Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-0032, Japan
| | - Yusuke Kurihara
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
- SHI Accelerator
Service Co. Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-0032, Japan
| | - Nobuki Nengaki
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
- SHI Accelerator
Service Co. Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-0032, Japan
| | - Katsushi Kumata
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Joji Yui
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Akiko Hatori
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Lin Xie
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yiding Zhang
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Kazunori Kawamura
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Ming-Rong Zhang
- Department
of Radiopharmaceuticals Development, Radiological Science Research
and Development Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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26
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Moreno JL, Miranda-Azpiazu P, García-Bea A, Younkin J, Cui M, Kozlenkov A, Ben-Ezra A, Voloudakis G, Fakira AK, Baki L, Ge Y, Georgakopoulos A, Morón JA, Milligan G, López-Giménez JF, Robakis NK, Logothetis DE, Meana JJ, González-Maeso J. Allosteric signaling through an mGlu2 and 5-HT2A heteromeric receptor complex and its potential contribution to schizophrenia. Sci Signal 2016; 9:ra5. [PMID: 26758213 DOI: 10.1126/scisignal.aab0467] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) can form multiprotein complexes (heteromers), which can alter the pharmacology and functions of the constituent receptors. Previous findings demonstrated that the Gq/11-coupled serotonin 5-HT2A receptor and the Gi/o-coupled metabotropic glutamate 2 (mGlu2) receptor-GPCRs that are involved in signaling alterations associated with psychosis-assemble into a heteromeric complex in the mammalian brain. In single-cell experiments with various mutant versions of the mGlu2 receptor, we showed that stimulation of cells expressing mGlu2-5-HT2A heteromers with an mGlu2 agonist led to activation of Gq/11 proteins by the 5-HT2A receptors. For this crosstalk to occur, one of the mGlu2 subunits had to couple to Gi/o proteins, and we determined the relative location of the Gi/o-contacting subunit within the mGlu2 homodimer of the heteromeric complex. Additionally, mGlu2-dependent activation of Gq/11, but not Gi/o, was reduced in the frontal cortex of 5-HT2A knockout mice and was reduced in the frontal cortex of postmortem brains from schizophrenic patients. These findings offer structural insights into this important target in molecular psychiatry.
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Affiliation(s)
- José L Moreno
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA. Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Patricia Miranda-Azpiazu
- Department of Pharmacology, University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain
| | - Aintzane García-Bea
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Department of Pharmacology, University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain
| | - Jason Younkin
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Meng Cui
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Alexey Kozlenkov
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Ariel Ben-Ezra
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Georgios Voloudakis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Amanda K Fakira
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Lia Baki
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Yongchao Ge
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | | | - José A Morón
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Graeme Milligan
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Juan F López-Giménez
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK. Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC-CSIC-UC), E-39011 Santander, Cantabria, Spain
| | - Nikolaos K Robakis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Diomedes E Logothetis
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - J Javier Meana
- Department of Pharmacology, University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), University of the Basque Country UPV/EHU, E-48940 Leioa, Bizkaia, Spain. BioCruces Health Research Institute, E-48903 Barakaldo, Bizkaia, Spain.
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA. Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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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.
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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.
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Shifting towards a model of mGluR5 dysregulation in schizophrenia: Consequences for future schizophrenia treatment. Neuropharmacology 2015; 115:73-91. [PMID: 26349010 DOI: 10.1016/j.neuropharm.2015.08.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/02/2015] [Accepted: 08/03/2015] [Indexed: 12/22/2022]
Abstract
Metabotropic glutamate receptor subtype 5 (mGluR5), encoded by the GRM5 gene, represents a compelling novel drug target for the treatment of schizophrenia. mGluR5 is a postsynaptic G-protein coupled glutamate receptor strongly linked with several critical cellular processes that are reported to be disrupted in schizophrenia. Accordingly, mGluR5 positive allosteric modulators show encouraging therapeutic potential in preclinical schizophrenia models, particularly for the treatment of cognitive dysfunctions against which currently available therapeutics are largely ineffective. More work is required to support the progression of mGluR5-targeting drugs into the clinic for schizophrenia treatment, although some obstacles may be overcome by comprehensively understanding how mGluR5 itself is involved in the neurobiology of the disorder. Several processes that are necessary for the regulation of mGluR5 activity have been identified, but not examined, in the context of schizophrenia. These processes include protein-protein interactions, dimerisation, subcellular trafficking, the impact of genetic variability or mutations on protein function, as well as epigenetic, post-transcriptional and post-translational processes. It is essential to understand these aspects of mGluR5 to determine whether they are affected in schizophrenia pathology, and to assess the consequences of mGluR5 dysfunction for the future use of mGluR5-based drugs. Here, we summarise the known processes that regulate mGluR5 and those that have already been studied in schizophrenia, and discuss the consequences of this dysregulation for current mGluR5 pharmacological strategies. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Atypical signaling of metabotropic glutamate receptor 1 in human melanoma cells. Biochem Pharmacol 2015; 98:182-9. [PMID: 26291396 DOI: 10.1016/j.bcp.2015.08.091] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/12/2015] [Indexed: 11/21/2022]
Abstract
The metabotropic glutamate 1 (mGlu1) receptor has emerged as a novel target for the treatment of metastatic melanoma and various other cancers. Our laboratory has demonstrated that a selective, non-competitive mGlu1 receptor antagonist slows human melanoma growth in vitro and in vivo. In this study, we sought to determine if the activation of a canonical G protein-dependent signal transduction cascade, which is often used as an output of mGlu1 receptor activity in neuronal cells, correlated with mGlu1 receptor-mediated melanoma cell viability. Glutamate, the endogenous ligand of mGlu1 receptors, significantly increased melanoma cell viability, but did not stimulate phosphoinositide (PI) hydrolysis in several human melanoma cell lines. In contrast, melanoma cell viability was not increased by quisqualate, a highly potent mGlu1 receptor agonist, or DHPG, a selective group I mGlu receptor agonist. Similarly to glutamate, quisqualate also failed to stimulate PI hydrolysis in mGlu1 receptor-expressing melanoma cells. These results suggest that the canonical G protein-dependent signal transduction cascade is not coupled to mGlu1 receptors in all human melanoma cells. On the other hand, dynamin inhibition selectively decreased viability of mGlu1 receptor-expressing melanoma cells, suggesting that a mechanism requiring internalization may control melanoma cell viability. Taken together, these data demonstrate that the approaches commonly used to study mGlu1 receptor function and signaling in other systems may be inappropriate for studying mGlu1 receptor-mediated melanoma cell viability.
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Yamasaki T, Fujinaga M, Yui J, Wakizaka H, Ohya T, Nengaki N, Ogawa M, Ikoma Y, Hatori A, Xie L, Kawamura K, Zhang MR. Improved Visualization and Specific Binding for Metabotropic Glutamate Receptor Subtype 1 (mGluR1) Using [11C]ITMM with Ultra-High Specific Activity in Small-Animal PET. PLoS One 2015; 10:e0130006. [PMID: 26076143 PMCID: PMC4468202 DOI: 10.1371/journal.pone.0130006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 04/29/2015] [Indexed: 12/15/2022] Open
Abstract
Metabotropic glutamate receptor subtype 1 (mGluR1) is a crucial target in the development of new medications to treat central nervous system (CNS) disorders. Recently, we developed N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-4-[11C]methoxy-N-methyl-benzamide ([11C]ITMM) as a useful positron emission tomography (PET) probe for mGluR1 in clinical studies. Here, we aimed to improve visualization and threshold of specific binding for mGluR1 using [11C]ITMM with ultra-high specific activity (SA) of > 3,500 GBq/μmol in rat brains. A two-tissue compartment model indicated large differences between the two SAs in the constants k3 and k4, representing binding ability for mGluR1, while constants K1 and k2 showed no differences. The total distribution volume (VT) values of conventional and ultra-high SA were 9.1 and 11.2 in the thalamus, 7.7 and 9.7 in the striatum, and 6.4 and 8.5 mL/cm3 in the substantia nigra, respectively. The specific binding of [11C]ITMM with ultra-high SA was significantly higher than the conventional SA, especially in the basal ganglia. Parametric PET images scaled with VT of the ultra-high SA clearly identified regional differences in the rat brain. In conclusion, PET studies using [11C]ITMM with ultra-high SA could sufficiently improve visualization and specific binding for mGluR1, which could help further understanding for mGluR1 functions in CNS disorders.
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Affiliation(s)
- Tomoteru Yamasaki
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
- * E-mail:
| | - Masayuki Fujinaga
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Joji Yui
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Hidekatsu Wakizaka
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Tomoyuki Ohya
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Nobuki Nengaki
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Masanao Ogawa
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Yoko Ikoma
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Akiko Hatori
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Lin Xie
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Kazunori Kawamura
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Ming-Rong Zhang
- Molucular Probe Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
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Kang HJ, Menlove K, Ma J, Wilkins A, Lichtarge O, Wensel TG. Selectivity and evolutionary divergence of metabotropic glutamate receptors for endogenous ligands and G proteins coupled to phospholipase C or TRP channels. J Biol Chem 2014; 289:29961-74. [PMID: 25193666 DOI: 10.1074/jbc.m114.574483] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
To define the upstream and downstream signaling specificities of metabotropic glutamate receptors (mGluR), we have examined the ability of representative mGluR of group I, II, and III to be activated by endogenous amino acids and catalyze activation of G proteins coupled to phospholipase C (PLC), or activation of G(i/o) proteins coupled to the ion channel TRPC4β. Fluorescence-based assays have allowed us to observe interactions not previously reported or clearly identified. We have found that the specificity for endogenous amino acids is remarkably stringent. Even at millimolar levels, structurally similar compounds do not elicit significant activation. As reported previously, the clear exception is L-serine-O-phosphate (L-SOP), which strongly activates group III mGluR, especially mGluR4,-6,-8 but not group I or II mGluR. Whereas L-SOP cannot activate mGluR1 or mGluR2, it acts as a weak antagonist for mGluR1 and a potent antagonist for mGluR2, suggesting that co-recognition of L-glutamate and L-SOP arose early in evolution, and was followed later by divergence of group I and group II mGluR versus group III in l-SOP responses. mGluR7 has low affinity and efficacy for activation by both L-glutamate and L-SOP. Molecular docking studies suggested that residue 74 corresponding to lysine in mGluR4 and asparagine in mGluR7 might play a key role, and, indeed, mutagenesis experiments demonstrated that mutating this residue to lysine in mGluR7 enhances the potency of L-SOP. Experiments with pertussis toxin and dominant-negative Gα(i/o) proteins revealed that mGluR1 couples strongly to TRPC4β through Gα(i/o), in addition to coupling to PLC through Gα(q/11).
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Affiliation(s)
- Hye Jin Kang
- From the Graduate Program in Structural and Computational Biology and Molecular Biophysics
| | - Kit Menlove
- From the Graduate Program in Structural and Computational Biology and Molecular Biophysics
| | - Jianpeng Ma
- From the Graduate Program in Structural and Computational Biology and Molecular Biophysics, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Bioengineering, Rice University, Houston, Texas 77005
| | - Angela Wilkins
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, and
| | - Olivier Lichtarge
- From the Graduate Program in Structural and Computational Biology and Molecular Biophysics, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, and
| | - Theodore G Wensel
- From the Graduate Program in Structural and Computational Biology and Molecular Biophysics, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and
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Goolam MA, Ward JH, Avlani VA, Leach K, Christopoulos A, Conigrave AD. Roles of intraloops-2 and -3 and the proximal C-terminus in signalling pathway selection from the human calcium-sensing receptor. FEBS Lett 2014; 588:3340-6. [PMID: 25080008 DOI: 10.1016/j.febslet.2014.07.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 07/03/2014] [Accepted: 07/16/2014] [Indexed: 12/24/2022]
Abstract
The calcium-sensing receptor (CaSR) couples to signalling pathways via intracellular loops 2 and 3, and the C-terminus. However, the requirements for signalling are largely undefined. We investigated the impacts of selected point mutations in iL-2 (F706A) and iL-3 (L797A and E803A), and a truncation of the C-terminus (R866X) on extracellular Ca(2+) (Ca(2+)o)-stimulated phosphatidylinositol-specific phospholipase-C (PI-PLC) and various other signalling responses. CaSR-mediated activation of PI-PLC was markedly attenuated in all four mutants and similar suppressions were observed for Ca(2+)o-stimulated ERK1/2 phosphorylation. Ca(2+)o-stimulated intracellular Ca(2+) (Ca(2+)i) mobilization, however, was relatively preserved for the iL-2 and iL-3 mutants and suppression of adenylyl cyclase was unaffected by either E803A or R866X. The CaSR selects for specific signalling pathways via the proximal C-terminus and key residues in iL-2, iL-3.
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Affiliation(s)
- Mahvash A Goolam
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - James H Ward
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Vimesh A Avlani
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Katie Leach
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur D Conigrave
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
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Kil KE, Zhu A, Zhang Z, Choi JK, Kura S, Gong C, Brownell AL. Development of [(123)I]IPEB and [(123)I]IMPEB as SPECT Radioligands for Metabotropic Glutamate Receptor Subtype 5. ACS Med Chem Lett 2014; 5:652-6. [PMID: 24944738 DOI: 10.1021/ml500007z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/06/2014] [Indexed: 12/17/2022] Open
Abstract
mGlu5 play an important role in physiology and pathology to various central nervous system (CNS) diseases. Several positron emission tomography (PET) radiotracers have been developed to explore the role of mGlu5 in brain disorders. However, there are no single photon emission computed tomography (SPECT) radioligands for mGlu5. Here we report development of [(123)I]IPEB ([(123)I]1) and [(123)I]IMPEB ([(123)I]2) as mGlu5 radioligands for SPECT. [(123)I]1 and [(123)I]2 were produced by copper(I) mediated aromatic halide displacement reactions. The SPECT imaging using mouse models demonstrated that [(123)I]1 readily entered the brain and accumulated specifically in mGlu5-rich regions of the brain such as striatum and hippocampus. However, in comparison to the corresponding PET tracer [(18)F]FPEB, [(123)I]1 showed faster washout from the brain. The binding ratios of the striatum and the hippocampus compared to the cerebellum for [(123)I]1 and [(18)F]FPEB were similar despite unfavorable pharmacokinetics of [(123)I]1. Further structural optimization of 1 may lead to more viable SPECT radiotracers for the imaging of mGlu5.
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Affiliation(s)
- Kun-Eek Kil
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Aijun Zhu
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Zhaoda Zhang
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Sreekanth Kura
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Chunyu Gong
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Anna-Liisa Brownell
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
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Yin S, Niswender CM. Progress toward advanced understanding of metabotropic glutamate receptors: structure, signaling and therapeutic indications. Cell Signal 2014; 26:2284-97. [PMID: 24793301 DOI: 10.1016/j.cellsig.2014.04.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 04/27/2014] [Indexed: 12/24/2022]
Abstract
The metabotropic glutamate (mGlu) receptors are a group of Class C seven-transmembrane spanning/G protein-coupled receptors (7TMRs/GPCRs). These receptors are activated by glutamate, one of the standard amino acids and the major excitatory neurotransmitter. By activating G protein-dependent and non-G protein-dependent signaling pathways, mGlus modulate glutamatergic transmission both in the periphery and throughout the central nervous system. Since the discovery of the first mGlu receptor, and especially during the last decade, a great deal of progress has been made in understanding the signaling, structure, pharmacological manipulation and therapeutic indications of the 8 mGlu members.
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Affiliation(s)
- Shen Yin
- Department of Pharmacology, Vanderbilt University Medical School, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical School, Nashville, TN 37232, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University Medical School, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical School, Nashville, TN 37232, USA.
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Noninvasive quantification of metabotropic glutamate receptor type 1 with [¹¹C]ITDM: a small-animal PET study. J Cereb Blood Flow Metab 2014; 34:606-12. [PMID: 24398932 PMCID: PMC3982087 DOI: 10.1038/jcbfm.2013.243] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/06/2013] [Accepted: 12/12/2013] [Indexed: 12/13/2022]
Abstract
Because of its role in multiple central nervous system (CNS) pathways, metabotropic glutamate receptor type 1 (mGluR1) is a crucial target in the development of pharmaceuticals for CNS disorders. N-[4-[6-(isopropylamino)-pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methyl-4-[(11)C]-methylbenzamide ([(11)C]ITDM) was recently developed as a positron emission tomography (PET) ligand for mGluR1. To devise a method for measurement of the binding potential (BPND) of [(11)C]ITDM to mGluR1, reference tissue methods aimed at replacing measurement of the arterial input function are desirable. In this study, we evaluated a noninvasive quantification method of mGluR1 with [(11)C]ITDM, demonstrating its accuracy using Huntington disease model R6/2 mice. The BPND measurements based on the Logan reference (Logan Ref) method have closely approximated that based on the arterial input method. We performed PET analysis with Logan Ref to assess its accuracy in quantifying the decline of mGluR1 expression in R6/2 mice. Significant decreases in BPND values in R6/2 mice were detected in cerebellum, thalamus, striatum, and cingulate cortex. We compared autoradiographs of R6/2 mouse brain sections with immunohistochemical images, and found a close correlation between changes in radioactive signal intensity and degree of mGluR1 expression. In conclusion, [(11)C]ITDM-PET is a promising tool for in vivo quantification of mGluR1 expression.
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Speyer CL, Hachem AH, Assi AA, Johnson JS, DeVries JA, Gorski DH. Metabotropic glutamate receptor-1 as a novel target for the antiangiogenic treatment of breast cancer. PLoS One 2014; 9:e88830. [PMID: 24633367 PMCID: PMC3954556 DOI: 10.1371/journal.pone.0088830] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 01/13/2014] [Indexed: 02/07/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are normally expressed in the central nervous system, where they mediate neuronal excitability and neurotransmitter release. Certain cancers, including melanoma and gliomas, express various mGluR subtypes that have been implicated as playing a role in disease progression. Recently, we detected metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1) in breast cancer and found that it plays a role in the regulation of cell proliferation and tumor growth. In addition to cancer cells, brain endothelial cells express mGluR1. In light of these studies, and because angiogenesis is both a prognostic indicator in cancer correlating with a poorer prognosis and a potential therapeutic target, we explored a potential role for mGluR1 in mediating endothelial cell (EC) proliferation and tumor-induced angiogenesis. GRM1 and mGluR1 were detected in various types of human ECs and, using mGluR1-specific inhibitors or shRNA silencing, we demonstrated that EC growth and Matrigel tube formation are dependent on mGluR1 signaling. In addition, loss of mGluR1 activity leads to reduced angiogenesis in a murine Matrigel sponge implant model as well as a murine tumor model. These results suggest a role for mGluR1 in breast cancer as a pro-angiogenic factor as well as a mediator of tumor progression. They also suggest mGluR1 as a potential new molecular target for the anti-angiogenic therapy of breast cancer.
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Affiliation(s)
- Cecilia L. Speyer
- Tumor Microenvironment Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Surgery, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ali H. Hachem
- University of Michigan, Dearborn, Michigan, United States of America
| | - Ali A. Assi
- University of Michigan, Dearborn, Michigan, United States of America
| | - Jennifer S. Johnson
- Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - John A. DeVries
- Department of Surgery, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - David H. Gorski
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Surgery, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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Metabotropic glutamate receptor-1 contributes to progression in triple negative breast cancer. PLoS One 2014; 9:e81126. [PMID: 24404125 PMCID: PMC3880256 DOI: 10.1371/journal.pone.0081126] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 10/09/2013] [Indexed: 12/31/2022] Open
Abstract
TNBC is an aggressive breast cancer subtype that does not express hormone receptors (estrogen and progesterone receptors, ER and PR) or amplified human epidermal growth factor receptor type 2 (HER2), and there currently exist no targeted therapies effective against it. Consequently, finding new molecular targets in triple negative breast cancer (TNBC) is critical to improving patient outcomes. Previously, we have detected the expression of metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1) in TNBC and observed that targeting glutamatergic signaling inhibits TNBC growth both in vitro and in vivo. In this study, we explored how mGluR1 contributes to TNBC progression, using the isogenic MCF10 progression series, which models breast carcinogenesis from nontransformed epithelium to malignant basal-like breast cancer. We observed that mGluR1 is expressed in human breast cancer and that in MCF10A cells, which model nontransformed mammary epithelium, but not in MCF10AT1 cells, which model atypical ductal hyperplasia, mGluR1 overexpression results in increased proliferation, anchorage-independent growth, and invasiveness. In contrast, mGluR1 knockdown results in a decrease in these activities in malignant MCF10CA1d cells. Similarly, pharmacologic inhibition of glutamatergic signaling in MCF10CA1d cells results in a decrease in proliferation and anchorage-independent growth. Finally, transduction of MCF10AT1 cells, which express c-Ha-ras, using a lentiviral construct expressing GRM1 results in transformation to carcinoma in 90% of resultant xenografts. We conclude that mGluR1 cooperates with other factors in hyperplastic mammary epithelium to contribute to TNBC progression and therefore propose that glutamatergic signaling represents a promising new molecular target for TNBC therapy.
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38
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Willard SS, Koochekpour S. Glutamate, glutamate receptors, and downstream signaling pathways. Int J Biol Sci 2013; 9:948-59. [PMID: 24155668 PMCID: PMC3805900 DOI: 10.7150/ijbs.6426] [Citation(s) in RCA: 194] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 07/11/2013] [Indexed: 12/23/2022] Open
Abstract
Glutamate is a nonessential amino acid, a major bioenergetic substrate for proliferating normal and neoplastic cells, and an excitatory neurotransmitter that is actively involved in biosynthetic, bioenergetic, metabolic, and oncogenic signaling pathways. Glutamate signaling activates a family of receptors consisting of metabotropic glutamate receptors (mGluRs) and ionotropic glutamate receptors (iGluRs), both of which have been implicated in chronic disabling brain disorders such as Schizophrenia and neurodegenerative diseases like Alzheimer's, Parkinson's, and multiple sclerosis. In this review, we discuss the structural and functional relationship of mGluRs and iGluRs and their downstream signaling pathways. The three groups of mGluRs, the associated second messenger systems, and subsequent activation of PI3K/Akt, MAPK, NFkB, PLC, and Ca/CaM signaling systems will be discussed in detail. The current state of human mGluR1a as one of the most important isoforms of Group I-mGluRs will be highlighted. The lack of studies on the human orthologues of mGluRs family will be outlined. We conclude that upon further study, human glutamate-initiated signaling pathways may provide novel therapeutic opportunities for a variety of non-malignant and malignant human diseases.
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Affiliation(s)
- Stacey S Willard
- Departments of Cancer Genetics and Urology, Center for Genetics and Pharmacology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY, USA
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Kumari R, Castillo C, Francesconi A. Agonist-dependent signaling by group I metabotropic glutamate receptors is regulated by association with lipid domains. J Biol Chem 2013; 288:32004-19. [PMID: 24045944 DOI: 10.1074/jbc.m113.475863] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluRs), mGluR1 and mGluR5, play critical functions in forms of activity-dependent synaptic plasticity and synapse remodeling in physiological and pathological states. Importantly, in animal models of fragile X syndrome, group I mGluR activity is abnormally enhanced, a dysfunction that may partly underlie cognitive deficits in the condition. Lipid rafts are cholesterol- and sphingolipid-enriched membrane domains that are thought to form transient signaling platforms for ligand-activated receptors. Many G protein-coupled receptors, including group I mGluRs, are present in lipid rafts, but the mechanisms underlying recruitment to these membrane domains remain incompletely understood. Here, we show that mGluR1 recruitment to lipid rafts is enhanced by agonist binding and is supported at least in part by an intact cholesterol recognition/interaction amino acid consensus (CRAC) motif in the receptor. Substitutions of critical residues in the motif reduce mGluR1 association with lipid rafts and agonist-induced, mGluR1-dependent activation of extracellular-signal-activated kinase1/2 MAP kinase (ERK-MAPK). We find that alteration of membrane cholesterol content or perturbation of lipid rafts regulates agonist-dependent activation of ERK-MAPK by group I mGluRs, suggesting a potential function for cholesterol as a positive allosteric modulator of receptor function(s). Together, these findings suggest that drugs that alter membrane cholesterol levels or directed to the receptor-cholesterol interface could be employed to modulate abnormal group I mGluR activity in neuropsychiatric conditions, including fragile X syndrome.
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Affiliation(s)
- Ranju Kumari
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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40
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Illuminating the activation mechanisms and allosteric properties of metabotropic glutamate receptors. Proc Natl Acad Sci U S A 2013; 110:E1416-25. [PMID: 23487753 DOI: 10.1073/pnas.1215615110] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In multimeric cell-surface receptors, the conformational changes of the extracellular ligand-binding domains (ECDs) associated with receptor activation remain largely unknown. This is the case for the dimeric metabotropic glutamate receptors even though a number of ECD structures have been solved. Here, using an innovative approach based on cell-surface labeling and FRET, we demonstrate that a reorientation of the ECDs is associated with receptor and G-protein activation. Our approach helps identify partial agonists and highlights allosteric interactions between the effector and binding domains. Any approach expected to stabilize the active conformation of the effector domain increased the agonist potency in stabilizing the active ECDs conformation. These data provide key information on the structural dynamics and drug action at metabotropic glutamate receptors and validate an approach for tackling such analysis on other receptors.
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41
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Matosin N, Newell KA. Metabotropic glutamate receptor 5 in the pathology and treatment of schizophrenia. Neurosci Biobehav Rev 2012; 37:256-68. [PMID: 23253944 DOI: 10.1016/j.neubiorev.2012.12.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/27/2012] [Accepted: 12/09/2012] [Indexed: 02/07/2023]
Abstract
Metabotropic glutamate receptor 5 (mGluR5) potentiates the NMDA receptor (NMDAR) in brain regions implicated in schizophrenia, making it a viable therapeutic target for the treatment of this disorder. mGluR5 positive allosteric modulators may represent a valuable novel strategy for schizophrenia treatment, given the favourable profile of effects in preclinical paradigms. However it remains unclear whether mGluR5 also plays a causal or epiphenomenal role in NMDAR dysfunction in schizophrenia. Animal and cellular data suggest involvement of mGluR5, whilst post-mortem human studies remain inconclusive. This review will explore the molecular, animal and human data to support and refute the involvement of mGluR5 in the pathology of schizophrenia. Furthermore, this review will discuss the potential of mGluR5 modulators in the therapy of schizophrenia as well as aspects of mGluR5 that require further characterisation.
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Affiliation(s)
- Natalie Matosin
- Centre for Translational Neuroscience, Illawarra Health and Medical Research Institute, School of Health Sciences, University of Wollongong, NSW 2522, Australia
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42
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Guimarães-Souza EM, Calaza KC. Selective activation of group III metabotropic glutamate receptor subtypes produces different patterns of γ-aminobutyric acid immunoreactivity and glutamate release in the retina. J Neurosci Res 2012; 90:2349-61. [PMID: 22987212 DOI: 10.1002/jnr.23123] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/10/2012] [Accepted: 07/16/2012] [Indexed: 11/06/2022]
Affiliation(s)
- E M Guimarães-Souza
- Neurobiology of the Retina Laboratory, Neuroscience Program and Departament of Neurobiology, Biology Institute, Federal Fluminense University, Rio de Janeiro, Brazil
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43
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Distinct roles of metabotropic glutamate receptor dimerization in agonist activation and G-protein coupling. Proc Natl Acad Sci U S A 2012; 109:16342-7. [PMID: 22988116 DOI: 10.1073/pnas.1205838109] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The eight metabotropic glutamate receptors (mGluRs) are key modulators of synaptic transmission and are considered promising targets for the treatment of various brain disorders. Whereas glutamate acts at a large extracellular domain, allosteric modulators have been identified that bind to the seven transmembrane domain (7TM) of these dimeric G-protein-coupled receptors (GPCRs). We show here that the dimeric organization of mGluRs is required for the modulation of active and inactive states of the 7TM by agonists, but is not necessary for G-protein activation. Monomeric mGlu2, either as an isolated 7TM or in full-length, purified and reconstituted into nanodiscs, couples to G proteins upon direct activation by a positive allosteric modulator. However, only a reconstituted full-length dimeric mGlu2 activates G protein upon glutamate binding, suggesting that dimerization is required for glutamate induced activation. These data show that, even for such well characterized GPCR dimers like mGluR2, a single 7TM is sufficient for G-protein coupling. Despite this observation, the necessity of dimeric architecture for signaling induced by the endogenous ligand glutamate confirms that the central core of signaling complex is dimeric.
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44
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Yasumatsu K, Ogiwara Y, Takai S, Yoshida R, Iwatsuki K, Torii K, Margolskee RF, Ninomiya Y. Umami taste in mice uses multiple receptors and transduction pathways. J Physiol 2011; 590:1155-70. [PMID: 22183726 DOI: 10.1113/jphysiol.2011.211920] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The distinctive umami taste elicited by l-glutamate and some other amino acids is thought to be initiated by G-protein-coupled receptors. Proposed umami receptors include heteromers of taste receptor type 1, members 1 and 3 (T1R1+T1R3), and metabotropic glutamate receptors 1 and 4 (mGluR1 and mGluR4). Multiple lines of evidence support the involvement of T1R1+T1R3 in umami responses of mice. Although several studies suggest the involvement of receptors other than T1R1+T1R3 in umami, the identity of those receptors remains unclear. Here, we examined taste responsiveness of umami-sensitive chorda tympani nerve fibres from wild-type mice and mice genetically lacking T1R3 or its downstream transduction molecule, the ion channel TRPM5. Our results indicate that single umami-sensitive fibres in wild-type mice fall into two major groups: sucrose-best (S-type) and monopotassium glutamate (MPG)-best (M-type). Each fibre type has two subtypes; one shows synergism between MPG and inosine monophosphate (S1, M1) and the other shows no synergism (S2, M2). In both T1R3 and TRPM5 null mice, S1-type fibres were absent, whereas S2-, M1- and M2-types remained. Lingual application of mGluR antagonists selectively suppressed MPG responses of M1- and M2-type fibres. These data suggest the existence of multiple receptors and transduction pathways for umami responses in mice. Information initiated from T1R3-containing receptors may be mediated by a transduction pathway including TRPM5 and conveyed by sweet-best fibres, whereas umami information from mGluRs may be mediated by TRPM5-independent pathway(s) and conveyed by glutamate-best fibres.
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Affiliation(s)
- Keiko Yasumatsu
- Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, 3-1-1 Maidashi, Higashi- ku, Fukuoka 812-8582, Japan
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45
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The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells. Vis Neurosci 2011; 29:31-9. [PMID: 21864448 DOI: 10.1017/s0952523811000204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractAmacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed.
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46
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Differential binding of calmodulin to group I metabotropic glutamate receptors regulates receptor trafficking and signaling. J Neurosci 2011; 31:5921-30. [PMID: 21508217 DOI: 10.1523/jneurosci.6253-10.2011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are G-protein-coupled receptors that modulate excitatory neurotransmission and synaptic plasticity. The group I mGluRs (mGluR1 and mGluR5) have long intracellular C-terminal domains, which interact with many proteins. Our previous studies identified calmodulin (CaM) as a strong regulator of mGluR5 trafficking and mGluR5-induced calcium signaling. Although it has been accepted that both mGluR1 and mGluR5 interact with CaM, we now show that CaM specifically binds mGluR5 and not mGluR1. We have identified a single critical residue in mGluR5 (L896) that is required for CaM binding. In mGluR1, mutation of the corresponding residue, V909, to leucine is sufficient to confer CaM binding to mGluR1. To investigate the functional effects of CaM binding, we examined the surface expression of mGluR1 and mGluR5 in hippocampal neurons. The mutation in mGluR1 (V909L) that confers CaM binding dramatically increases mGluR1 surface expression, whereas the analogous mutation in mGluR5 that disrupts CaM binding (L896V) decreases mGluR5 surface expression. In addition, the critical residue that alters CaM binding regulates mGluR internalization. Furthermore, we find that mGluR-mediated AMPA receptor endocytosis is enhanced by CaM binding to group I mGluRs. Finally, we show that calcium responses evoked by group I mGluRs are modulated by these mutations, which regulate CaM binding. Our findings elucidate a critical mechanism that specifically affects mGluR5 trafficking and signaling, and distinguishes mGluR1 and mGluR5 regulation.
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Speyer CL, Smith JS, Banda M, DeVries JA, Mekani T, Gorski DH. Metabotropic glutamate receptor-1: a potential therapeutic target for the treatment of breast cancer. Breast Cancer Res Treat 2011; 132:565-73. [PMID: 21681448 DOI: 10.1007/s10549-011-1624-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 06/02/2011] [Indexed: 12/24/2022]
Abstract
Metabotropic glutamate receptors are G-protein-coupled receptors normally expressed in the central nervous system where they mediate neuronal excitability, synaptic plasticity, and feedback inhibition of neurotransmitter release. However, recent data suggest that these receptors are also expressed and functional in some cancers, most notably melanoma. We detected the expression of metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1) in triple negative breast cancer cells and evaluated its role in regulating the pro-proliferative phenotype of these cells. mGluR1 inhibitors (Riluzole or BAY36-7620) inhibited the proliferation of triple negative breast cancer cells in a time- and dose-dependent manner and this inhibition correlated with increased apoptosis as demonstrated by increase in PARP cleavage products and Annexin V staining. mGluR1 knockdown using Lentiviral constructs expressing shRNA targeting GRM1 also inhibited proliferation compared to non-silencing controls. In addition, treatment of mice bearing MDA-MB-231 xenografts with Riluzole or BAY36-7620, by intraperitoneal injection, resulted in a significant reduction in tumor volume of up to 80%. Moreover, Riluzole was effective against triple negative breast cancer xenografts in mice at doses equivalent to those currently being used in humans for the treatment of amyotrophic lateral sclerosis. Our observations implicate mGluR1 and glutamate signaling as a promising new molecular target for the treatment of breast cancer. Even more promising, Riluzole, because it is an oral drug that can be administered with low toxicity, represents a promising approach in the treatment of triple negative breast cancer.
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Affiliation(s)
- Cecilia L Speyer
- Breast Cancer Biology Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI, USA
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Tateyama M, Kubo Y. The intra-molecular activation mechanisms of the dimeric metabotropic glutamate receptor 1 differ depending on the type of G proteins. Neuropharmacology 2011; 61:832-41. [PMID: 21672544 DOI: 10.1016/j.neuropharm.2011.05.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/19/2011] [Accepted: 05/25/2011] [Indexed: 11/19/2022]
Abstract
Metabotropic glutamate receptor 1 (mGlu1) functions as a homodimer and activates not only the Gq but also the Gi/o and Gs pathways. Because of the dimeric configuration, different pathways could be activated either through the glutamate-bound subunit (cis-activation) and/or the other one (trans-activation). We here examined whether the intra-molecular activation mechanisms in the mGlu1 differ depending on the type of coupling G proteins, using various combinations of mGlu1 constructs that lack glutamate binding and/or G-protein coupling. The cis- or trans-activation alone was confirmed to trigger the Gq-coupled intracellular Ca(2+) transient. In contrast, the Gi/o-coupled G protein-dependent inward rectifying potassium (GIRK) channels were not activated either through the cis- or trans-activation alone. When one subunit of dimeric mGlu1 lacked the G-protein coupling, a significant decrease in the glutamate-induced GIRK current density was also observed. As the G protein-coupling-deficient subunit did not decrease the cell surface expression of mGlu1 and the Gq-coupled Ca(2+) transient, it was suggested that the coupling deficiency in one subunit of mGlu1 attenuates the Gi/o but not Gq coupling. In conclusion, multiple G-protein signaling was differentially activated by different intra-molecular activation mechanisms of the dimeric mGlu1.
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Affiliation(s)
- Michihiro Tateyama
- Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan.
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Lee J, Kim I, Oh SR, Ko SJ, Lim MK, Kim DG, Kim CH. Regulation of DREAM Expression by Group I mGluR. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:95-100. [PMID: 21660149 DOI: 10.4196/kjpp.2011.15.2.95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 03/18/2011] [Accepted: 03/23/2011] [Indexed: 12/12/2022]
Abstract
DREAM (downstream regulatory element antagonistic modulator) is a calcium-binding protein that regulates dynorphin expression, promotes potassium channel surface expression, and enhances presenilin processing in an expression level-dependent manner. However, no molecular mechanism has yet explained how protein levels of DREAM are regulated. Here we identified group I mGluR (mGluR1/5) as a positive regulator of DREAM protein expression. Overexpression of mGluR1/5 increased the cellular level of DREAM. Up-regulation of DREAM resulted in increased DREAM protein in both the nucleus and cytoplasm, where the protein acts as a transcriptional repressor and a modulator of its interacting proteins, respectively. DHPG (3,5-dihydroxyphenylglycine), a group I mGluR agonist, also up-regulated DREAM expression in cortical neurons. These results suggest that group I mGluR is the first identified receptor that may regulate DREAM activity in neurons.
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Affiliation(s)
- Jinu Lee
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 120-752, Korea
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Guimarães-Souza E, Gardino P, De Mello F, Calaza K. A calcium-dependent glutamate release induced by metabotropic glutamate receptors I/II promotes GABA efflux from amacrine cells via a transporter-mediated process. Neuroscience 2011; 179:23-31. [DOI: 10.1016/j.neuroscience.2011.01.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 01/17/2011] [Accepted: 01/20/2011] [Indexed: 10/18/2022]
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