1
|
Hofmann CS, Carrington S, Keller AN, Gregory KJ, Niswender CM. Regulation and functional consequences of mGlu 4 RNA editing. RNA (NEW YORK, N.Y.) 2021; 27:1220-1240. [PMID: 34244459 PMCID: PMC8457003 DOI: 10.1261/rna.078729.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Metabotropic glutamate receptor 4 (mGlu4) is one of eight mGlu receptors within the Class C G protein-coupled receptor superfamily. mGlu4 is primarily localized to the presynaptic membrane of neurons where it functions as an auto and heteroreceptor controlling synaptic release of neurotransmitter. mGlu4 is implicated in numerous disorders and is a promising drug target; however, more remains to be understood about its regulation and pharmacology. Using high-throughput sequencing, we have validated and quantified an adenosine-to-inosine (A-to-I) RNA editing event that converts glutamine 124 to arginine in mGlu4; additionally, we have identified a rare but novel K129R site. Using an in vitro editing assay, we then validated the pre-mRNA duplex that allows for editing by ADAR enzymes and predicted its conservation across the mammalian species. Structural modeling of the mGlu4 protein predicts the Q124R substitution to occur in the B helix of the receptor that is critical for receptor dimerization and activation. Interestingly, editing of a receptor homodimer does not disrupt G protein activation in response to the endogenous agonist, glutamate. Using an assay designed to specifically measure heterodimer populations at the surface, however, we found that Q124R substitution decreased the propensity of mGlu4 to heterodimerize with mGlu2 and mGlu7 Our study is the first to extensively describe the extent and regulatory factors of RNA editing of mGlu4 mRNA transcripts. In addition, we have proposed a novel functional consequence of this editing event that provides insights regarding its effects in vivo and expands the regulatory capacity for mGlu receptors.
Collapse
MESH Headings
- Adenosine Deaminase/genetics
- Adenosine Deaminase/metabolism
- Amino Acid Sequence
- Animals
- Base Pairing
- Base Sequence
- Birds
- Cerebral Cortex/cytology
- Cerebral Cortex/metabolism
- Corpus Striatum/cytology
- Corpus Striatum/metabolism
- HEK293 Cells
- Hippocampus/cytology
- Hippocampus/metabolism
- Humans
- Models, Molecular
- Neurons/cytology
- Neurons/metabolism
- Nucleic Acid Conformation
- Point Mutation
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- RNA Editing
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Metabotropic Glutamate/chemistry
- Receptors, Metabotropic Glutamate/genetics
- Receptors, Metabotropic Glutamate/metabolism
- Reptiles
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- Christopher S Hofmann
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Sheridan Carrington
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Andrew N Keller
- Department of Pharmacology and Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Karen J Gregory
- Department of Pharmacology and Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, USA
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee 37203, USA
| |
Collapse
|
2
|
Buceta I, Elezgarai I, Rico‐Barrio I, Gerrikagoitia I, Puente N, Grandes P. Deletion of the cannabinoid CB
1
receptor impacts on the ultrastructure of the cerebellar parallel fiber‐Purkinje cell synapses. J Comp Neurol 2019; 528:1041-1052. [DOI: 10.1002/cne.24808] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 10/09/2019] [Accepted: 10/31/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Ianire Buceta
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Izaskun Elezgarai
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Irantzu Rico‐Barrio
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Inmaculada Gerrikagoitia
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
- Division of Medical Sciences University of Victoria Victoria British Columbia Canada
| |
Collapse
|
3
|
Khatri SN, Wu WC, Yang Y, Pugh JR. Direction of action of presynaptic GABA A receptors is highly dependent on the level of receptor activation. J Neurophysiol 2019; 121:1896-1905. [PMID: 30892973 DOI: 10.1152/jn.00779.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Many synapses, including parallel fiber synapses in the cerebellum, express presynaptic GABAA receptors. However, reports of the functional consequences of presynaptic GABAA receptor activation are variable across synapses, from inhibition to enhancement of transmitter release. We find that presynaptic GABAA receptor function is bidirectional at parallel fiber synapses depending on GABA concentration and modulation of GABAA receptors in mice. Activation of GABAA receptors by low GABA concentrations enhances glutamate release, whereas activation of receptors by higher GABA concentrations inhibits release. Furthermore, blocking GABAB receptors reduces GABAA receptor currents and shifts presynaptic responses toward greater enhancement of release across a wide range of GABA concentrations. Conversely, enhancing GABAA receptor currents with ethanol or neurosteroids shifts responses toward greater inhibition of release. The ability of presynaptic GABAA receptors to enhance or inhibit transmitter release at the same synapse depending on activity level provides a new mechanism for fine control of synaptic transmission by GABA and may explain conflicting reports of presynaptic GABAA receptor function across synapses. NEW & NOTEWORTHY GABAA receptors are widely expressed at presynaptic terminals in the central nervous system. However, previous reports have produced conflicting results on the function of these receptors at different synapses. We show that presynaptic GABAA receptor function is strongly dependent on the level of receptor activation. Low levels of receptor activation enhance transmitter release, whereas higher levels of activation inhibit release at the same synapses. This provides a novel mechanism by which presynaptic GABAA receptors fine-tune synaptic transmission.
Collapse
Affiliation(s)
- Shailesh N Khatri
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Wan-Chen Wu
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Ying Yang
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas.,Xiangya School of Medicine, Central South University , Changsha, Hunan , China
| | - Jason R Pugh
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas.,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| |
Collapse
|
4
|
Muzyka VV, Brooks M, Badea TC. Postnatal developmental dynamics of cell type specification genes in Brn3a/Pou4f1 Retinal Ganglion Cells. Neural Dev 2018; 13:15. [PMID: 29958540 PMCID: PMC6025728 DOI: 10.1186/s13064-018-0110-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 06/06/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND About 20-30 distinct Retinal Ganglion Cell (RGC) types transmit visual information from the retina to the brain. The developmental mechanisms by which RGCs are specified are still largely unknown. Brn3a is a member of the Brn3/Pou4f transcription factor family, which contains key regulators of RGC postmitotic specification. In particular, Brn3a ablation results in the loss of RGCs with small, thick and dense dendritic arbors ('midget-like' RGCs), and morphological changes in other RGC subpopulations. To identify downstream molecular mechanisms underlying Brn3a effects on RGC numbers and morphology, our group recently performed a RNA deep sequencing screen for Brn3a transcriptional targets in mouse RGCs and identified 180 candidate transcripts. METHODS We now focus on a subset of 28 candidate genes encoding potential cell type determinant proteins. We validate and further define their retinal expression profile at five postnatal developmental time points between birth and adult stage, using in situ hybridization (ISH), RT-PCR and fluorescent immunodetection (IIF). RESULTS We find that a majority of candidate genes are enriched in the ganglion cell layer during early stages of postnatal development, but dynamically change their expression profile. We also document transcript-specific expression differences for two example candidates, using RT-PCR and ISH. Brn3a dependency could be confirmed by ISH and IIF only for a fraction of our candidates. CONCLUSIONS Amongst our candidate Brn3a target genes, a majority demonstrated ganglion cell layer specificity, however only around two thirds showed Brn3a dependency. Some were previously implicated in RGC type specification, while others have known physiological functions in RGCs. Only three genes were found to be consistently regulated by Brn3a throughout postnatal retina development - Mapk10, Tusc5 and Cdh4.
Collapse
Affiliation(s)
| | - Matthew Brooks
- Genomics Core, Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, NIH, Building 6, Room 331B Center Drive, Bethesda, MD, 20892-0610, USA
| | - Tudor Constantin Badea
- Retinal Circuit Development & Genetics Unit, Building 6, Room 331B Center Drive, Bethesda, MD, 20892-0610, USA.
| |
Collapse
|
5
|
Jenkins BG, Zhu A, Poutiainen P, Choi JK, Kil KE, Zhang Z, Kuruppu D, Aytan N, Dedeoglu A, Brownell AL. Functional modulation of G-protein coupled receptors during Parkinson disease-like neurodegeneration. Neuropharmacology 2016; 108:462-73. [PMID: 26581500 PMCID: PMC4896842 DOI: 10.1016/j.neuropharm.2015.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 09/24/2015] [Accepted: 11/06/2015] [Indexed: 01/11/2023]
Abstract
G-protein coupled dopamine and metabotropic glutamate receptors (mGlu) can modulate neurotransmission during Parkinson's disease (PD)-like neurodegeneration. PET imaging studies in a unilateral dopamine denervation model (6-OHDA) showed a significant inverse correlation of presynaptic mGlu4 and postsynaptic mGlu5 expression in the striatum and rapidly declining mGlu4 and enhanced mGlu5 expression in the hippocampus during progressive degeneration over time. Immunohistochemical studies verified the decreased mGlu4 expression in the hippocampus on the lesion side but did not show difference in mGlu5 expression between lesion and control side. Pharmacological MRI studies showed enhanced hemodynamic response in several brain areas on the lesion side compared to the control side after challenge with mGlu4 positive allosteric modulator or mGlu5 negative allosteric modulator. However, mGlu4 response was biphasic having short enhancement followed by negative response on both sides of brain. Studies in mGlu4 expressing cells demonstrated that glutamate induces cooperative increase in binding of mGlu4 ligands - especially at high glutamate levels consistent with in vivo concentration. This suggests that mGlu allosteric modulators as drug candidates will be highly sensitive to changes in glutamate concentration and hence metabolic state. These experiments demonstrate the importance of the longitudinal imaging studies to investigate temporal changes in receptor functions to obtain individual response for experimental drugs.
Collapse
Affiliation(s)
- Bruce G Jenkins
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Aijun Zhu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Pekka Poutiainen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Kun-Eek Kil
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Zhaoda Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Darshini Kuruppu
- Surgical Oncology, Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - Nurgul Aytan
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, MA 02130, USA
| | - Alpaslan Dedeoglu
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, MA 02130, USA; Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anna-Liisa Brownell
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA.
| |
Collapse
|
6
|
Peterlik D, Flor PJ, Uschold-Schmidt N. The Emerging Role of Metabotropic Glutamate Receptors in the Pathophysiology of Chronic Stress-Related Disorders. Curr Neuropharmacol 2016; 14:514-39. [PMID: 27296643 PMCID: PMC4983752 DOI: 10.2174/1570159x13666150515234920] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 04/04/2015] [Accepted: 05/12/2015] [Indexed: 12/28/2022] Open
Abstract
Chronic stress-related psychiatric conditions such as anxiety, depression, and alcohol abuse are an enormous public health concern. The etiology of these pathologies is complex, with psychosocial stressors being among the most frequently discussed risk factors. The brain glutamatergic neurotransmitter system has often been found involved in behaviors and pathophysiologies resulting from acute stress and fear. Despite this, relatively little is known about the role of glutamatergic system components in chronic psychosocial stress, neither in rodents nor in humans. Recently, drug discovery efforts at the metabotropic receptor subtypes of the glutamatergic system (mGlu1-8 receptors) led to the identification of pharmacological tools with emerging potential in psychiatric conditions. But again, the contribution of individual mGlu subtypes to the manifestation of physiological, molecular, and behavioral consequences of chronic psychosocial stress remains still largely unaddressed. The current review will describe animal models typically used to analyze acute and particularly chronic stress conditions, including models of psychosocial stress, and there we will discuss the emerging roles for mGlu receptor subtypes. Indeed, accumulating evidence indicates relevance and potential therapeutic usefulness of mGlu2/3 ligands and mGlu5 receptor antagonists in chronic stress-related disorders. In addition, a role for further mechanisms, e.g. mGlu7-selective compounds, is beginning to emerge. These mechanisms are important to be analyzed in chronic psychosocial stress paradigms, e.g. in the chronic subordinate colony housing (CSC) model. We summarize the early results and discuss necessary future investigations, especially for mGlu5 and mGlu7 receptor blockers, which might serve to suggest improved therapeutic strategies to treat stress-related disorders.
Collapse
Affiliation(s)
| | - Peter J Flor
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
| | - Nicole Uschold-Schmidt
- Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany.
| |
Collapse
|
7
|
Ossowska K, Wardas J, Berghauzen-Maciejewska K, Głowacka U, Kuter K, Pilc A, Zorn SH, Doller D. Lu AF21934, a positive allosteric modulator of mGlu4 receptors, reduces the harmaline-induced hyperactivity but not tremor in rats. Neuropharmacology 2014; 83:28-35. [PMID: 24726309 DOI: 10.1016/j.neuropharm.2014.03.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/18/2014] [Accepted: 03/31/2014] [Indexed: 12/19/2022]
Abstract
Harmaline induces tremor in animals resembling essential tremor which has been suggested to result from activation of the glutamatergic olivo-cerebellar projection. The aim of the present study was to examine the effects of systemic administration of Lu AF21934, a brain-penetrating positive allosteric modulator of the metabotropic glutamate receptor 4 (mGlu4), on the harmaline-induced tremor and other forms of motor activity in rats using fully automated Force Plate Actimeters. The influence of harmaline on the mGlu4 mRNA expression in the cerebellum and inferior olive was analysed by in situ hybridization. Harmaline at a dose of 15 mg/kg (ip) triggered tremor which was manifested by an increase in the power within 9-15 Hz band and in the tremor index (a difference in power between bands 9-15 Hz and 0-8 Hz). Harmaline induced a biphasic effect on mobility, initially inhibiting the exploratory locomotor activity of rats (0-30 min after administration), followed by an increase in their basic activity. Lu AF21934 (0.5-5 mg/kg sc) did not influence tremor but at doses of 0.5 and 2.5 mg/kg reversed harmaline-induced hyperactivity. MGlu4 mRNA expression was high in the cerebellar cortex and low in the inferior olive. Repeated harmaline (15 mg/kg ip once a day for 5 days] decreased mGlu4 mRNA in the cerebellum and inferior olive. The present study indicates that the mGlu4 stimulation counteracts hyperactivity induced by harmaline which suggests the involvement of cerebellar glutamatergic transmission in this process. In contrast, neuronal mechanisms involved in tremor seem to be insensitive to the stimulation of mGlu4.
Collapse
Affiliation(s)
- Krystyna Ossowska
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna St., 31-343 Kraków, Poland.
| | - Jadwiga Wardas
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna St., 31-343 Kraków, Poland
| | - Klemencja Berghauzen-Maciejewska
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna St., 31-343 Kraków, Poland
| | - Urszula Głowacka
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna St., 31-343 Kraków, Poland
| | - Katarzyna Kuter
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna St., 31-343 Kraków, Poland
| | - Andrzej Pilc
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, 12, Smętna St., 31-343 Kraków, Poland
| | - Stevin H Zorn
- Discovery Chemistry & DMPK, Lundbeck Research USA, 215 College Road, Paramus, NJ 07652, USA
| | - Dario Doller
- Discovery Chemistry & DMPK, Lundbeck Research USA, 215 College Road, Paramus, NJ 07652, USA
| |
Collapse
|