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Acarón Ledesma H, Ding J, Oosterboer S, Huang X, Chen Q, Wang S, Lin MZ, Wei W. Dendritic mGluR2 and perisomatic Kv3 signaling regulate dendritic computation of mouse starburst amacrine cells. Nat Commun 2024; 15:1819. [PMID: 38418467 PMCID: PMC10901804 DOI: 10.1038/s41467-024-46234-7] [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: 12/13/2021] [Accepted: 02/20/2024] [Indexed: 03/01/2024] Open
Abstract
Dendritic mechanisms driving input-output transformation in starburst amacrine cells (SACs) are not fully understood. Here, we combine two-photon subcellular voltage and calcium imaging and electrophysiological recording to determine the computational architecture of mouse SAC dendrites. We found that the perisomatic region integrates motion signals over the entire dendritic field, providing a low-pass-filtered global depolarization to dendrites. Dendrites integrate local synaptic inputs with this global signal in a direction-selective manner. Coincidental local synaptic inputs and the global motion signal in the outward motion direction generate local suprathreshold calcium transients. Moreover, metabotropic glutamate receptor 2 (mGluR2) signaling in SACs modulates the initiation of calcium transients in dendrites but not at the soma. In contrast, voltage-gated potassium channel 3 (Kv3) dampens fast voltage transients at the soma. Together, complementary mGluR2 and Kv3 signaling in different subcellular regions leads to dendritic compartmentalization and direction selectivity, highlighting the importance of these mechanisms in dendritic computation.
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Affiliation(s)
- Héctor Acarón Ledesma
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, IL, 60637, USA
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Jennifer Ding
- The Committee on Neurobiology Graduate Program, The University of Chicago, Chicago, IL, 60637, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Swen Oosterboer
- The Committee on Neurobiology Graduate Program, The University of Chicago, Chicago, IL, 60637, USA
| | - Xiaolin Huang
- The Committee on Neurobiology Graduate Program, The University of Chicago, Chicago, IL, 60637, USA
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
| | - Qiang Chen
- The Committee on Computational Neuroscience Graduate Program, The University of Chicago, Chicago, IL, 60637, USA
- Department of Physiology & Biophysics, University of Washington, Seattle, WA, 98195, USA
| | - Sui Wang
- Department of Ophthalmology, Stanford University, Stanford, CA, 94305, USA
| | - Michael Z Lin
- Department of Neurobiology, Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Wei Wei
- Department of Neurobiology and the Neuroscience Institute, The University of Chicago, Chicago, IL, 60637, USA.
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2
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Metabotropic Glutamate Receptors at Ribbon Synapses in the Retina and Cochlea. Cells 2022; 11:cells11071097. [PMID: 35406660 PMCID: PMC8998116 DOI: 10.3390/cells11071097] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 02/01/2023] Open
Abstract
Our senses define our view of the world. They allow us to adapt to environmental stimuli and are essential for communication and social behaviour. For most humans, seeing and hearing are central senses for their daily life. Our eyes and ears respond to an extraordinary broad range of stimuli covering about 12 log units of light intensity or acoustic power, respectively. The cellular basis is represented by sensory cells (photoreceptors in the retina and inner hair cells in the cochlea) that convert sensory inputs into electrical signals. Photoreceptors and inner hair cells have developed a specific pre-synaptic structure, termed synaptic ribbon, that is decorated with numerous vesicles filled with the excitatory neurotransmitter glutamate. At these ribbon synapses, glutamatergic signal transduction is guided by distinct sets of metabotropic glutamate receptors (mGluRs). MGluRs belong to group II and III of the receptor classification can inhibit neuronal activity, thus protecting neurons from overstimulation and subsequent degeneration. Consequently, dysfunction of mGluRs is associated with vision and hearing disorders. In this review, we introduce the principle characteristics of ribbon synapses and describe group II and III mGluRs in these fascinating structures in the retina and cochlea.
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3
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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: 24] [Impact Index Per Article: 6.0] [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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4
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Folci A, Mirabella F, Fossati M. Ubiquitin and Ubiquitin-Like Proteins in the Critical Equilibrium between Synapse Physiology and Intellectual Disability. eNeuro 2020; 7:ENEURO.0137-20.2020. [PMID: 32719102 PMCID: PMC7544190 DOI: 10.1523/eneuro.0137-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/08/2020] [Accepted: 06/17/2020] [Indexed: 01/04/2023] Open
Abstract
Posttranslational modifications (PTMs) represent a dynamic regulatory system that precisely modulates the functional organization of synapses. PTMs consist in target modifications by small chemical moieties or conjugation of lipids, sugars or polypeptides. Among them, ubiquitin and a large family of ubiquitin-like proteins (UBLs) share several features such as the structure of the small protein modifiers, the enzymatic cascades mediating the conjugation process, and the targeted aminoacidic residue. In the brain, ubiquitination and two UBLs, namely sumoylation and the recently discovered neddylation orchestrate fundamental processes including synapse formation, maturation and plasticity, and their alteration is thought to contribute to the development of neurological disorders. Remarkably, emerging evidence suggests that these pathways tightly interplay to modulate the function of several proteins that possess pivotal roles for brain homeostasis as well as failure of this crosstalk seems to be implicated in the development of brain pathologies. In this review, we outline the role of ubiquitination, sumoylation, neddylation, and their functional interplay in synapse physiology and discuss their implication in the molecular pathogenesis of intellectual disability (ID), a neurodevelopmental disorder that is frequently comorbid with a wide spectrum of brain pathologies. Finally, we propose a few outlooks that might contribute to better understand the complexity of these regulatory systems in regard to neuronal circuit pathophysiology.
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Affiliation(s)
- Alessandra Folci
- Humanitas Clinical and Research Center-IRCCS, via Manzoni 56, 20089, Rozzano (MI), Italy
| | - Filippo Mirabella
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve 9 Emanuele - Milan, Italy
| | - Matteo Fossati
- Humanitas Clinical and Research Center-IRCCS, via Manzoni 56, 20089, Rozzano (MI), Italy
- CNR-Institute of Neuroscience, via Manzoni 56, 20089, Rozzano (MI), Italy
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5
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Srivastava A, Das B, Yao AY, Yan R. Metabotropic Glutamate Receptors in Alzheimer's Disease Synaptic Dysfunction: Therapeutic Opportunities and Hope for the Future. J Alzheimers Dis 2020; 78:1345-1361. [PMID: 33325389 PMCID: PMC8439550 DOI: 10.3233/jad-201146] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence of neuritic plaques and neurofibrillary tangles. The impaired synaptic plasticity and dendritic loss at the synaptic level is an early event associated with the AD pathogenesis. The abnormal accumulation of soluble oligomeric amyloid-β (Aβ), the major toxic component in amyloid plaques, is viewed to trigger synaptic dysfunctions through binding to several presynaptic and postsynaptic partners and thus to disrupt synaptic transmission. Over time, the abnormalities in neural transmission will result in cognitive deficits, which are commonly manifested as memory loss in AD patients. Synaptic plasticity is regulated through glutamate transmission, which is mediated by various glutamate receptors. Here we review recent progresses in the study of metabotropic glutamate receptors (mGluRs) in AD cognition. We will discuss the role of mGluRs in synaptic plasticity and their modulation as a possible strategy for AD cognitive improvement.
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Affiliation(s)
- Akriti Srivastava
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Brati Das
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Annie Y. Yao
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Riqiang Yan
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
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Klotz L, Wendler O, Frischknecht R, Shigemoto R, Schulze H, Enz R. Localization of group II and III metabotropic glutamate receptors at pre- and postsynaptic sites of inner hair cell ribbon synapses. FASEB J 2019; 33:13734-13746. [PMID: 31585509 DOI: 10.1096/fj.201901543r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the CNS binding to a variety of glutamate receptors. Metabotropic glutamate receptors (mGluR1 to mGluR8) can act excitatory or inhibitory, depending on associated signal cascades. Expression and localization of inhibitory acting mGluRs at inner hair cells (IHCs) in the cochlea are largely unknown. Here, we analyzed expression of mGluR2, mGluR3, mGluR4, mGluR6, mGluR7, and mGluR8 and investigated their localization with respect to the presynaptic ribbon of IHC synapses. We detected transcripts for mGluR2, mGluR3, and mGluR4 as well as for mGluR7a, mGluR7b, mGluR8a, and mGluR8b splice variants. Using receptor-specific antibodies in cochlear wholemounts, we found expression of mGluR2, mGluR4, and mGluR8b close to presynaptic ribbons. Super resolution and confocal microscopy in combination with 3-dimensional reconstructions indicated a postsynaptic localization of mGluR2 that overlaps with postsynaptic density protein 95 on dendrites of afferent type I spiral ganglion neurons. In contrast, mGluR4 and mGluR8b were expressed at the presynapse close to IHC ribbons. In summary, we localized in detail 3 mGluR types at IHC ribbon synapses, providing a fundament for new therapeutical strategies that could protect the cochlea against noxious stimuli and excitotoxicity.-Klotz, L., Wendler, O., Frischknecht, R., Shigemoto, R., Schulze, H., Enz, R. Localization of group II and III metabotropic glutamate receptors at pre- and postsynaptic sites of inner hair cell ribbon synapses.
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Affiliation(s)
- Lisa Klotz
- Institute for Biochemistry (Emil-Fischer-Zentrum), Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Olaf Wendler
- Division of Phoniatrics and Pediatric Audiology, Department of Otorhinolaryngology, Head and Neck Surgery, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Renato Frischknecht
- Department of Biology, Animal Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Holger Schulze
- Department of Otorhinolaryngology, Head and Neck Surgery, Experimental Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Ralf Enz
- Institute for Biochemistry (Emil-Fischer-Zentrum), Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
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7
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Salemi LM, Maitland MER, McTavish CJ, Schild-Poulter C. Cell signalling pathway regulation by RanBPM: molecular insights and disease implications. Open Biol 2018; 7:rsob.170081. [PMID: 28659384 PMCID: PMC5493780 DOI: 10.1098/rsob.170081] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 06/01/2017] [Indexed: 12/25/2022] Open
Abstract
RanBPM (Ran-binding protein M, also called RanBP9) is an evolutionarily conserved, ubiquitous protein which localizes to both nucleus and cytoplasm. RanBPM has been implicated in the regulation of a number of signalling pathways to regulate several cellular processes such as apoptosis, cell adhesion, migration as well as transcription, and plays a critical role during development. In addition, RanBPM has been shown to regulate pathways implicated in cancer and Alzheimer's disease, implying that RanBPM has important functions in both normal and pathological development. While its functions in these processes are still poorly understood, RanBPM has been identified as a component of a large complex, termed the CTLH (C-terminal to LisH) complex. The yeast homologue of this complex functions as an E3 ubiquitin ligase that targets enzymes of the gluconeogenesis pathway. While the CTLH complex E3 ubiquitin ligase activity and substrates still remain to be characterized, the high level of conservation between the complexes in yeast and mammals infers that the CTLH complex could also serve to promote the degradation of specific substrates through ubiquitination, therefore suggesting the possibility that RanBPM's various functions may be mediated through the activity of the CTLH complex.
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Affiliation(s)
- Louisa M Salemi
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Matthew E R Maitland
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Christina J McTavish
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Caroline Schild-Poulter
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
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8
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Das S, Suresh B, Kim HH, Ramakrishna S. RanBPM: a potential therapeutic target for modulating diverse physiological disorders. Drug Discov Today 2017; 22:1816-1824. [PMID: 28847759 DOI: 10.1016/j.drudis.2017.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 06/26/2017] [Accepted: 08/21/2017] [Indexed: 02/06/2023]
Abstract
The Ran-binding protein microtubule-organizing center (RanBPM) is a highly conserved nucleocytoplasmic protein involved in a variety of intracellular signaling pathways that control diverse cellular functions. RanBPM interacts with proteins that are linked to various diseases, including Alzheimer's disease (AD), schizophrenia (SCZ), and cancer. In this article, we define the characteristics of the scaffolding protein RanBPM and focus on its interaction partners in diverse physiological disorders, such as neurological diseases, fertility disorders, and cancer.
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Affiliation(s)
- Soumyadip Das
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Bharathi Suresh
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, 03722, South Korea.
| | - Hyongbum Henry Kim
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, 03722, South Korea; Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, South Korea; Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea; Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, South Korea.
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 04763, South Korea; College of Medicine, Hanyang University, Seoul, 04763, South Korea.
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9
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Koren D, Grove JCR, Wei W. Cross-compartmental Modulation of Dendritic Signals for Retinal Direction Selectivity. Neuron 2017; 95:914-927.e4. [PMID: 28781167 DOI: 10.1016/j.neuron.2017.07.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/08/2017] [Accepted: 07/19/2017] [Indexed: 11/19/2022]
Abstract
Compartmentalized signaling in dendritic subdomains is critical for the function of many central neurons. In the retina, individual dendritic sectors of a starburst amacrine cell (SAC) are preferentially activated by different directions of linear motion, indicating limited signal propagation between the sectors. However, the mechanism that regulates this propagation is poorly understood. Here, we find that metabotropic glutamate receptor 2 (mGluR2) signaling, which acts on voltage-gated calcium channels in SACs, selectively restricts cross-sector signal propagation in SACs, but does not affect local dendritic computation within individual sectors. mGluR2 signaling ensures sufficient electrotonic isolation of dendritic sectors to prevent their depolarization during non-preferred motion, yet enables controlled multicompartmental signal integration that enhances responses to preferred motion. Furthermore, mGluR2-mediated dendritic compartmentalization in SACs is important for the functional output of direction-selective ganglion cells (DSGCs). Therefore, our results directly link modulation of dendritic compartmentalization to circuit-level encoding of motion direction in the retina.
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Affiliation(s)
- David Koren
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA; Interdisciplinary Scientist Training Program, The University of Chicago, Chicago, IL 60637, USA
| | - James C R Grove
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA
| | - Wei Wei
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA.
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Ritter-Makinson SL, Paquet M, Bogenpohl JW, Rodin RE, Chris Yun C, Weinman EJ, Smith Y, Hall RA. Group II metabotropic glutamate receptor interactions with NHERF scaffold proteins: Implications for receptor localization in brain. Neuroscience 2017; 353:58-75. [PMID: 28392297 DOI: 10.1016/j.neuroscience.2017.03.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/29/2017] [Accepted: 03/29/2017] [Indexed: 12/13/2022]
Abstract
The group II metabotropic glutamate receptors mGluR2 and mGluR3 are key modulators of glutamatergic neurotransmission. In order to identify novel Group II metabotropic glutamate receptor (mGluR)-interacting partners, we screened the C-termini of mGluR2 and mGluR3 for interactions with an array of PDZ domains. These screens identified the Na+/H+ exchanger regulatory factors 1 and 2 (NHERF-1 & -2) as candidate interacting partners. Follow-up co-immunoprecipitation studies demonstrated that both mGluR2 and mGluR3 can associate with NHERF-1 and NHERF-2 in a cellular context. Functional studies revealed that disruption of PDZ interactions with mGluR2 enhanced receptor signaling to Akt. However, further studies of mGluR2 and mGluR3 signaling in astrocytes in which NHERF expression was reduced by gene knockout (KO) and/or siRNA knockdown techniques revealed that the observed differences in signaling between WT and mutant mGluR2 were likely not due to disruption of interactions with the NHERF proteins. Electron microscopic analyses revealed that Group II mGluRs were primarily expressed in glia and unmyelinated axons in WT, NHERF-1 and NHERF-2 KO mice, but the relative proportion of labeled axons over glial processes was higher in NHERF-2 KO mice than in controls and NHERF-1 KO mice. Interestingly, our anatomical studies also revealed that loss of either NHERF protein results in ventriculomegaly, which may be related to the high incidence of hydrocephaly that has previously been observed in NHERF-1 KO mice. Together, these studies support a role for NHERF-1 and NHERF-2 in regulating the distribution of Group II mGluRs in the murine brain, while conversely the effects of the mGluR2/3 PDZ-binding motifs on receptor signaling are likely mediated by interactions with other PDZ scaffold proteins beyond the NHERF proteins.
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Affiliation(s)
| | - Maryse Paquet
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - James W Bogenpohl
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
| | - Rachel E Rodin
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - C Chris Yun
- Department of Medicine, Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA 30329, USA
| | - Edward J Weinman
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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Choi JH, Park JY, Park SP, Lee H, Han S, Park KH, Suh YH. Regulation of mGluR7 trafficking by SUMOylation in neurons. Neuropharmacology 2015; 102:229-35. [PMID: 26631532 DOI: 10.1016/j.neuropharm.2015.11.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 10/13/2015] [Accepted: 11/22/2015] [Indexed: 11/26/2022]
Abstract
SUMOylation is a post-translational modification by which Small Ubiquitin-like MOdifier (SUMO) proteins are covalently linked to the lysine residues of target proteins via an enzymatic cascade. SUMOylation at the synapse plays an important regulatory role in a wide variety of neuronal function such as synapse formation and receptor endocytosis. The metabotropic glutamate receptor type 7 (mGluR7), a presynaptic G protein-coupled receptor, modulates excitatory neurotransmission and synaptic plasticity by inhibiting neurotransmitter release. The SUMO conjugation of mGluR7 has been demonstrated from several in vitro studies, however, it has not been successful in identifying SUMOylation of full-length mGluR7 in vivo. In the present study, we find that mGluR7 at Lys889 is a target of SUMO conjugation, which is impeded by SUMO-specific isopeptidase SENP1 in HEK 293T cells. In addition, we identify SUMOylated mGluR7 both in brain and primary cortical neurons, that is reduced by the treatment of L-AP4, mGluR7 agonist. We find that deSUMOylated mutation in mGluR7 or overexpression of SENP-1 markedly increases mGluR7 internalization in hippocampal neurons, indicating that endocytosis of mGluR7 is enhanced by the reduced SUMO conjugation of mGluR7. Furthermore, Ser862 phosphorylation facilitates SUMO conjugation of mGluR7. Together, these results reveal that SUMOylation of mGluR7 at Lys889 is required for stable surface expression of mGluR7 in neurons.
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Affiliation(s)
- Ji-Hee Choi
- Department of Pharmacology and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea
| | - Ji-Young Park
- Department of Pharmacology and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea
| | - Seung Pyo Park
- Department of Biomedical Sciences and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 110-799, South Korea
| | - Hyojin Lee
- Department of Biomedical Sciences and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 110-799, South Korea
| | - Seulki Han
- Department of Biomedical Sciences and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 110-799, South Korea
| | - Kyung Hee Park
- Department of Pharmacology and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea
| | - Young Ho Suh
- Department of Pharmacology and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea; Department of Biomedical Sciences and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, 110-799, South Korea.
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12
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Wei JD, Kim JY, Kim AK, Jang SK, Kim JH. RanBPM protein acts as a negative regulator of BLT2 receptor to attenuate BLT2-mediated cell motility. J Biol Chem 2013; 288:26753-63. [PMID: 23928309 DOI: 10.1074/jbc.m113.470260] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BLT2, a low affinity receptor for leukotriene B4 (LTB4), is a member of the G protein-coupled receptor family and is involved in many signal transduction pathways associated with various cellular phenotypes, including chemotactic motility. However, the regulatory mechanism for BLT2 has not yet been demonstrated. To understand the regulatory mechanism of BLT2, we screened and identified the proteins that bind to BLT2. Using a yeast two-hybrid assay with the BLT2 C-terminal domain as bait, we found that RanBPM, a previously proposed scaffold protein, interacts with BLT2. We demonstrated the specific interaction between BLT2 and RanBPM by GST pulldown assay and co-immunoprecipitation assay. To elucidate the biological function of the RanBPM-BLT2 interaction, we evaluated the effects of RanBPM overexpression or knockdown. We found that BLT2-mediated motility was severely attenuated by RanBPM overexpression and that knockdown of endogenous RanBPM by shRNA strongly promoted BLT2-mediated motility, suggesting a negative regulatory function of RanBPM toward BLT2. Furthermore, we observed that the addition of BLT2 ligands caused the dissociation of BLT2 and RanBPM, thus releasing the negative regulatory effect of RanBPM. Finally, we propose that Akt-induced BLT2 phosphorylation at residue Thr(355), which occurs after the addition of BLT2 ligands, is a potential mechanism by which BLT2 dissociates from RanBPM, resulting in stimulation of BLT2 signaling. Taken together, our results suggest that RanBPM acts as a negative regulator of BLT2 signaling to attenuate BLT2-mediated cell motility.
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Affiliation(s)
- Jun-Dong Wei
- From the School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul 136-701
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Palavicini JP, Lloyd BN, Hayes CD, Bianchi E, Kang DE, Dawson-Scully K, Lakshmana MK. RanBP9 Plays a Critical Role in Neonatal Brain Development in Mice. PLoS One 2013; 8:e66908. [PMID: 23840553 PMCID: PMC3694151 DOI: 10.1371/journal.pone.0066908] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 05/10/2013] [Indexed: 11/29/2022] Open
Abstract
RanBP9 is known to act as a scaffolding protein bringing together a variety of cell surface receptors and intracellular targets thereby regulating functions as diverse as neurite and axonal outgrowth, cell morphology, cell proliferation, myelination, gonad development, myofibrillogenesis and migration of neuronal precursors. Though RanBP9 is ubiquitously expressed in all tissues, brain is one of the organs with the highest expression levels of RanBP9. In the neurons, RanBP9 is localized mostly in the cytoplasm but also in the neurites and dendritic processes. We recently demonstrated that RanBP9 plays pathogenic role in Alzheimer’s disease. To understand the role of RanBP9 in the brain, here we generated RanBP9 null mice by gene-trap based strategy. Most of Ran−/− mice die neonatally due to defects in the brain growth and development. The major defects include smaller cortical plate (CP), robustly enlarged lateral ventricles (LV) and reduced volume of hippocampus (HI). The lethal phenotype is due to a suckling defect as evidenced by lack of milk in the stomachs even several hours after parturition. The complex somatosensory system which is required for a behavior such as suckling appears to be compromised in Ran−/− mice due to under developed CP. Most importantly, RanBP9 phenotype is similar to ERK1/2 double knockout and the neural cell adhesion receptor, L1CAM knockout mice. Both ERK1 and L1CAM interact with RanBP9. Thus, RanBP9 appears to control brain growth and development through signaling mechanisms involving ERK1 and L1CAM receptor.
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Affiliation(s)
- Juan Pablo Palavicini
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
| | - Brandon Noel Lloyd
- Department of Biological Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, Florida, United States of America
| | - Crystal D. Hayes
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
| | - Elisabetta Bianchi
- Laboratory of Immuneregulation, Department of Immunology, Institut Pasteur, Paris, France
| | - David E. Kang
- Department of Molecular Medicine, USF Health Byrd Alzheimer’s Institute, Tampa, Florida, United States of America
| | - Ken Dawson-Scully
- Department of Biological Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, Florida, United States of America
| | - Madepalli K. Lakshmana
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
- * E-mail:
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14
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Abstract
RanBPM is a multimodular scaffold protein that interacts with a great variety of molecules including nuclear, cytoplasmic, and membrane proteins. By building multiprotein complexes, RanBPM is thought to regulate various signaling pathways, especially in the immune and nervous system. However, the diversity of these interactions does not facilitate the identification of its precise mechanism of action, and therefore the physiological role of RanBPM still remains unclear. Recently, RanBPM has been shown to be critical for the fertility of both genders in mouse. Although mechanistically it is still unclear how RanBPM affects gametogenesis, the data collected so far suggest that it is a key player in this process. Here, we examine the RanBPM sterility phenotype in the context of other genetic mutations affecting mouse gametogenesis to investigate whether this scaffold protein affects the function of other known proteins whose deficiency results in similar sterility phenotypes.
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Affiliation(s)
- Sandrine Puverel
- Neural Development Section, Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, Maryland, USA.
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15
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Diversity of metabotropic glutamate receptor-interacting proteins and pathophysiological functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:63-79. [PMID: 22351051 DOI: 10.1007/978-3-7091-0932-8_3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In the mammalian brain, the large majority of excitatory synapses express pre- and postsynaptic glutamate receptors. These are ion channels and G protein-coupled membrane proteins that are organized into functional signaling complexes. Here, we will review the nature and pathophysiological functions of the scaffolding proteins associated to these receptors, focusing on the G protein-coupled subtypes.
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16
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Suresh B, Ramakrishna S, Baek KH. Diverse roles of the scaffolding protein RanBPM. Drug Discov Today 2011; 17:379-87. [PMID: 22094242 DOI: 10.1016/j.drudis.2011.10.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/08/2011] [Accepted: 10/31/2011] [Indexed: 11/27/2022]
Abstract
Ran-binding protein microtubule-organizing center (RanBPM) appears to function as a scaffolding protein in several signal transduction pathways. RanBPM is a crucial component of multiprotein complexes that regulate the cellular function by modulating and/or assembling with a wide range of proteins in different intracellular regions and thereby mediate diverse cellular functions. This suggests a role for RanBPM as a scaffolding protein. In this article, we have summarized the diverse functions of RanBPM and its interacting partners that have been investigated to date. Also, we have categorized the role of RanBPM into four divisions: RanBPM as a modulator/protein stabilizer, regulator of transcription activity, cell cycle and neurological functions.
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Affiliation(s)
- Bharathi Suresh
- Department of Biomedical Science, CHA University, CHA General Hospital, Seoul 135-081, Republic of Korea
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SUMO E3 ligases are expressed in the retina and regulate SUMOylation of the metabotropic glutamate receptor 8b. Biochem J 2011; 435:365-71. [PMID: 21288202 DOI: 10.1042/bj20101854] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The central nervous system regulates neuronal excitability by macromolecular signalling complexes that consist of functionally related proteins, including neurotransmitter receptors, enzymes and scaffolds. The composition of these signal complexes is regulated by post-translational modifications, such as phosphorylation and SUMOylation (SUMO is small ubiquitin-related modifier). In the present study, we searched for proteins interacting with the intracellular C-termini of the metabotropic glutamate receptors mGluR8a and mGluR8b and identified proteins of the SUMOylation and NEDDylation machinery. The SUMO E3 ligases Pias1 [Pias is protein inhibitor of activated STAT (signal transducer and activator of transcription)] and Pias3L interacted strongly with mGluR8b, and were co-localized with the E2-conjugating Ubc9, SUMO1 and mGluR8b in cell bodies present in the ganglion cell layer of the mammalian retina. SUMO1 conjugation of Lys882, present in a bona fide consensus sequence for SUMOylation (VKSE) in the mGluR8b C-terminus, was enhanced by addition of Pias1, consistent with an interaction between both proteins. Mutation of Lys882 to arginine reduced, but did not abolish, mGluR8b SUMOylation. Co-mutating a second lysine residue (Lys903) located in the mGluR8b isoform-specific C-terminus largely prevented SUMO1 conjugation by Ubc9. Modelling studies suggested that Lys903 contacts Ubc9 and thus is part of the non-canonical SUMOylation site VKSG. In summary, the results of the present study show in vivo SUMOylation of the complete mGluR8b and co-localize proteins of the SUMOylation machinery in the retina.
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Wilkinson KA, Henley JM. Analysis of metabotropic glutamate receptor 7 as a potential substrate for SUMOylation. Neurosci Lett 2011; 491:181-6. [PMID: 21255632 PMCID: PMC3122152 DOI: 10.1016/j.neulet.2011.01.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/09/2011] [Accepted: 01/12/2011] [Indexed: 01/28/2023]
Abstract
Group III metabotropic glutamate receptors (mGluRs) undergo post-translational modification by SUMO in in vitro assays but the SUMOylation of full-length mGluRs in mammalian cells has not been reported. Here we investigated SUMOylation of mGluR7 in HEK293 cells and primary cortical neurons in an attempt to confirm SUMOylation and define physiological effects on mGluR7 function. Using a recombinant bacterial expression assay we validated in vitro SUMOylation of the C-terminal domain of mGluR7 by both SUMO-1 and SUMO-2 and show that a single lysine residue (K889) in mGluR7 is required for SUMOylation. However, using a range of approaches, we were unable to detect SUMOylation of full-length mGluR7 in either heterologous cells or neurons. Further, we observed no differences in receptor stability or surface expression between wild-type and a non-SUMOylatable point mutant mGluR7. Thus, our results question whether mGluR7, and by implication other group III mGluRs, are physiologically relevant neuronal SUMO substrates.
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Affiliation(s)
| | - Jeremy M. Henley
- Corresponding author. Tel.: +44 117 9546 449; fax: +44 117 9291 687.
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19
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Scantlebury N, Zhao XL, Rodriguez Moncalvo VG, Camiletti A, Zahanova S, Dineen A, Xin JH, Campos AR. The Drosophila gene RanBPM functions in the mushroom body to regulate larval behavior. PLoS One 2010; 5:e10652. [PMID: 20498842 PMCID: PMC2871054 DOI: 10.1371/journal.pone.0010652] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 04/12/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In vertebrates, Ran-Binding Protein in the Microtubule Organizing Center (RanBPM) appears to function as a scaffolding protein in a variety of signal transduction pathways. In Drosophila, RanBPM is implicated in the regulation of germ line stem cell (GSC) niche organization in the ovary. Here, we addressed the role of RanBPM in nervous system function in the context of Drosophila larval behavior. METHODOLOGY/PRINCIPAL FINDINGS We report that in Drosophila, RanBPM is required for larval feeding, light-induced changes in locomotion, and viability. RanBPM is highly expressed in the Kenyon cells of the larval mushroom body (MB), a structure well studied for its role in associative learning in Drosophila and other insects. RanBPM mutants do not display major disruption in nervous system morphology besides reduced proliferation. Expression of the RanBPM gene in the Kenyon cells is sufficient to rescue all behavioral phenotypes. Through genetic epistasis experiments, we demonstrate that RanBPM participates with the Drosophila orthologue of the Fragile X Mental Retardation Protein (FMRP) in the development of neuromuscular junction (NMJ). CONCLUSIONS/SIGNIFICANCE We demonstrate that the RanBPM gene functions in the MB neurons for larval behavior. Our results suggest a role for this gene in an FMRP-dependent process. Taken together our findings point to a novel role for the MB in larval behavior.
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Affiliation(s)
- Nadia Scantlebury
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Xiao Li Zhao
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | | | - Alison Camiletti
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Stacy Zahanova
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Aidan Dineen
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Ji-Hou Xin
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Ana Regina Campos
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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20
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Rex EB, Rankin ML, Yang Y, Lu Q, Gerfen CR, Jose PA, Sibley DR. Identification of RanBP 9/10 as interacting partners for protein kinase C (PKC) gamma/delta and the D1 dopamine receptor: regulation of PKC-mediated receptor phosphorylation. Mol Pharmacol 2010; 78:69-80. [PMID: 20395553 DOI: 10.1124/mol.110.063727] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We reported previously that ethanol treatment regulates D(1) receptor phosphorylation and signaling in a protein kinase C (PKC) delta- and PKCgamma-dependent fashion by a mechanism that may involve PKC isozyme-specific interacting proteins. Using a PKC isozyme-specific coimmunoprecipitation approach coupled to mass spectrometry, we report the identification of RanBP9 and RanBP10 as novel interacting proteins for both PKCgamma and PKCdelta. Both RanBP9 and RanBP10 were found to specifically coimmunoprecipitate with both PKCgamma and PKCdelta; however, this association did not seem to mediate the ethanol regulation of the PKCs. It is noteworthy that the D(1) receptor was also found to specifically coimmunoprecipitate with RanBP9/10 from human embryonic kidney (HEK) 293T cells and with endogenous RanBP9 from rat kidney. RanBP9 and RanBP10 were also found to colocalize at the cellular level with the D(1) receptor in both kidney and brain tissue. Although overexpression of RanBP9 or RanBP10 in HEK293T cells did not seem to alter the kinase activities of either PKCdelta or PKCgamma, both RanBP proteins regulated D(1) receptor phosphorylation, signaling, and, in the case of RanBP9, expression. Specifically, overexpression of either RanBP9 or RanBP10 enhanced basal D(1) receptor phosphorylation, which was associated with attenuation of D(1) receptor-stimulated cAMP accumulation. Moreover, treatment of cells with select PKC inhibitors blocked the RanBP9/10-dependent increase in basal receptor phosphorylation, suggesting that phosphorylation of the receptor by PKC is regulated by RanBP9/10. These data support the idea that RanBP9 and RanBP10 may function as signaling integrators and dictate the efficient regulation of D(1) receptor signaling by PKCdelta and PKCgamma.
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Affiliation(s)
- Elizabeth B Rex
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Niswender CM, Conn PJ. Metabotropic glutamate receptors: physiology, pharmacology, and disease. Annu Rev Pharmacol Toxicol 2010; 50:295-322. [PMID: 20055706 DOI: 10.1146/annurev.pharmtox.011008.145533] [Citation(s) in RCA: 1300] [Impact Index Per Article: 92.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabotropic glutamate receptors (mGluRs) are family C G-protein-coupled receptors that participate in the modulation of synaptic transmission and neuronal excitability throughout the central nervous system. The mGluRs bind glutamate within a large extracellular domain and transmit signals through the receptor protein to intracellular signaling partners. A great deal of progress has been made in determining the mechanisms by which mGluRs are activated, proteins with which they interact, and orthosteric and allosteric ligands that can modulate receptor activity. The widespread expression of mGluRs makes these receptors particularly attractive drug targets, and recent studies continue to validate the therapeutic utility of mGluR ligands in neurological and psychiatric disorders such as Alzheimer's disease, Parkinson's disease, anxiety, depression, and schizophrenia.
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Affiliation(s)
- Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37212, USA.
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Chang Y, Paramasivam M, Girgenti MJ, Walikonis RS, Bianchi E, LoTurco JJ. RanBPM regulates the progression of neuronal precursors through M-phase at the surface of the neocortical ventricular zone. Dev Neurobiol 2010; 70:1-15. [PMID: 19790105 DOI: 10.1002/dneu.20750] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Many of the mitoses that produce pyramidal neurons in neocortex occur at the dorsolateral surface of the lateral ventricles in the embryo. RanBPM was found in a yeast two-hybrid screen to potentially interact with citron kinase (CITK), a protein shown previously to localize to the surface of the lateral ventricles and to be essential to neurogenic mitoses. Similar to its localization in epithelia, RanBPM protein is concentrated at the adherens junctions in developing neocortex. The biochemical interaction between CITK and RanBPM was confirmed in coimmunoprecipitation and protein overlay experiments. To test for a functional role of RanPBM in vivo, we used in utero RNAi. RanBPM RNAi decreased the polarization of CITK to the ventricular surface, increased the number of cells in mitosis, and decreased the number of cells in cytokinesis. Finally, the effect of RanBPM knockdown on mitosis was reversed in embryos mutant for CITK. Together, these results indicate that RanBPM, potentially through interaction with CITK, plays a role in the progression of neocortical precursors through M-phase at the ventricular surface.
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Affiliation(s)
- Yoonjeung Chang
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
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Talbot JN, Skifter DA, Bianchi E, Monaghan DT, Toews ML, Murrin LC. Regulation of mu opioid receptor internalization by the scaffold protein RanBPM. Neurosci Lett 2009; 466:154-8. [PMID: 19788913 DOI: 10.1016/j.neulet.2009.09.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 09/24/2009] [Accepted: 09/24/2009] [Indexed: 10/20/2022]
Abstract
Mu opioid receptors (MOP) are transducers of the pharmacological effects of many opioid drugs, including analgesia and tolerance/dependence. Previously, we observed increased MOP signaling during postnatal development that was not associated with increased MOP or G protein expression. A yeast two-hybrid screen of a human brain cDNA library using the MOP C-terminus as bait identified RanBPM as a potential MOP-interacting protein. RanBPM has been recognized as a multi-functional scaffold protein that interacts with a variety of signaling receptors/proteins. Co-immunoprecipitation studies in HEK293 cells indicated that RanBPM constitutively associates with MOP. Functionally, RanBPM had no effect on MOP-mediated inhibition of adenylyl cyclase, yet reduced agonist-induced endocytosis of MOP. Mechanistically, RanBPM interfered with beta arrestin2-GFP translocation stimulated by MOP but not alpha(1B)-adrenergic receptor activation, indicating selectivity of action. Our findings suggest that RanBPM is a novel MOP-interacting protein that negatively regulates receptor internalization without altering MOP signaling through adenylyl cyclase.
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Affiliation(s)
- Jeffery N Talbot
- Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800, USA
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Lakshmana MK, Chung JY, Wickramarachchi S, Tak E, Bianchi E, Koo EH, Kang DE. A fragment of the scaffolding protein RanBP9 is increased in Alzheimer's disease brains and strongly potentiates amyloid-beta peptide generation. FASEB J 2009; 24:119-27. [PMID: 19729516 DOI: 10.1096/fj.09-136457] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Increasing biochemical and genetic evidence indicates that the amyloid-beta (Abeta) peptide derived from amyloid precursor protein (APP) plays a central role in Alzheimer's disease (AD) pathogenesis. We previously reported that RanBP9 promotes Abeta generation by scaffolding APP/BACE1/LRP complexes together. Interestingly, the RanBP9-Delta1/N60 (residues 1-392) deletion mutant interacted much more strongly with APP/BACE1/LRP than full-length RanBP9. In this study, we found that RanBP9-N60, a processed form of RanBP9 virtually identical to the RanBP9-Delta1/N60 mutant, was strongly increased in AD brains compared with controls. To evaluate the potential pathogenic consequences of this phenotype, we studied the differential biological properties of full-length RanBP9 vs. RanBP9-Delta1/N60 in HEK293T and Neuro-2A cells. The RanBP9-Delta1/N60 fragment, which lacks a nuclear localization signal, displayed enhanced cytoplasmic vs. nuclear localization and >3-fold enhanced stability than full-length RanBP9. Importantly, RanBP9-Delta1/N60, which contains the LisH dimerization domain, retained the capacity to form self-interacting multimeric complexes and increased Abeta generation by approximately 5-fold over vector controls, more potent than the approximately 3-fold increase seen by full-length RanBP9. Taken together, these data indicate that RanBP9-N60 may further drive the amyloid cascade in AD and that the proteolytic processing of RanBP9 may be an attractive therapeutic target.
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Affiliation(s)
- Madepalli K Lakshmana
- Department of Neurosciences, University of California-San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
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Hohberger B, Enz R. Cereblon is expressed in the retina and binds to voltage-gated chloride channels. FEBS Lett 2009; 583:633-7. [DOI: 10.1016/j.febslet.2009.01.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 12/22/2008] [Accepted: 01/05/2009] [Indexed: 11/16/2022]
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