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Chetwynd SA, Andrews S, Inglesfield S, Delon C, Ktistakis NT, Welch HCE. Functions and mechanisms of the GPCR adaptor protein Norbin. Biochem Soc Trans 2023; 51:1545-1558. [PMID: 37503670 PMCID: PMC10586782 DOI: 10.1042/bst20221349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 06/27/2023] [Accepted: 07/07/2023] [Indexed: 07/29/2023]
Abstract
Norbin (Neurochondrin, NCDN) is a highly conserved 79 kDa adaptor protein that was first identified more than a quarter of a century ago as a gene up-regulated in rat hippocampus upon induction of long-term potentiation. Most research has focussed on the role of Norbin in the nervous system, where the protein is highly expressed. Norbin regulates neuronal morphology and synaptic plasticity, and is essential for normal brain development and homeostasis. Dysregulation of Norbin is linked to a variety of neurological conditions. Recently, Norbin was shown to be expressed in myeloid cells as well as neurons. Myeloid-cell specific deletion revealed an important role of Norbin as a suppressor of neutrophil-derived innate immunity. Norbin limits the ability of neutrophils to clear bacterial infections by curbing the responsiveness of these cells to inflammatory and infectious stimuli. Mechanistically, Norbin regulates cell responses through binding to its interactors, in particular to a wide range of G protein-coupled receptors (GPCRs). Norbin association with GPCRs controls GPCR trafficking and signalling. Other important Norbin interactors are the Rac guanine-nucleotide exchange factor P-Rex1 and protein kinase A. Downstream signalling pathways regulated by Norbin include ERK, Ca2+ and the small GTPase Rac. Here, we review the current understanding of Norbin structure, expression and its roles in health and disease. We also explore Norbin signalling through its interactors, with a particular focus on GPCR trafficking and signalling. Finally, we discuss avenues that could be pursued in the future to increase our understanding of Norbin biology.
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Affiliation(s)
| | - Simon Andrews
- Bioinformatics Facility, Babraham Institute, Cambridge, U.K
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Schwarzwald A, Salmen A, León Betancourt AX, Diem L, Hammer H, Radojewski P, Rebsamen M, Kamber N, Chan A, Hoepner R, Friedli C. Anti- neurochondrin antibody as a biomarker in primary autoimmune cerebellar ataxia-a case report and review of the literature. Eur J Neurol 2023; 30:1135-1147. [PMID: 36437687 DOI: 10.1111/ene.15648] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND PURPOSE Neuronal autoantibodies can support the diagnosis of primary autoimmune cerebellar ataxia (PACA). Knowledge of PACA is still sparce. This article aims to highlight the relevance of anti-neurochondrin antibodies and possible therapeutical consequences in people with PACA. METHODS This is a case presentation and literature review of PACA associated with anti-neurochondrin antibodies. RESULTS A 33-year-old man noticed reduced control of the right leg in May 2020. During his first clinic appointment at our institution in September 2021, he complained about gait imbalance, fine motor disorders, tremor, intermittent diplopia and slurred speech. He presented a pancerebellar syndrome with stance, gait and limb ataxia, scanning speech and oculomotor dysfunction. Within 3 months the symptoms progressed. An initial cerebral magnetic resonance imaging, June 2020, was normal, but follow-up imaging in October 2021 and July 2022 revealed marked cerebellar atrophy (29% volume loss). Cerebrospinal fluid analysis showed lymphocytic pleocytosis of 11 x 103 /L (normal range 0-4) and oligoclonal bands type II. Anti-neurochondrin antibodies (immunoglobulin G) were detected in serum (1:10,000) and cerebrospinal fluid (1:320, by cell-based indirect immunofluorescence assay and immunoblot, analysed by the EUROIMMUN laboratory). After ruling out alternative causes and neoplasia, diagnosis of PACA was given and immunotherapy (steroids and cyclophosphamide) was started in January 2022. In March 2022 a stabilization of disease was observed. CONCLUSION Cerebellar ataxia associated with anti-neurochondrin antibodies has only been described in 19 cases; however, the number of unrecognized PACAs may be higher. As anti-neurochondrin antibodies target an intracellular antigen and exhibit a mainly cytotoxic T-cell-mediated pathogenesis, important therapeutic implications may result. Because of the severe and rapid clinical progression, aggressive immunotherapy was warranted. This case highlights the need for rapid diagnosis and therapy in PACA, as stabilization and even improvement of symptoms are attainable.
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Affiliation(s)
- Anina Schwarzwald
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
- Clinic Bethesda, Neurorehabilitation, Parkinson Centre, Epileptology, Tschugg, Switzerland
| | - Anke Salmen
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | | | - Lara Diem
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Helly Hammer
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Piotr Radojewski
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Michael Rebsamen
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Nicole Kamber
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Andrew Chan
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Robert Hoepner
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Christoph Friedli
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
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Abstract
We determined the prevalence of autoantibodies against an extended number of established and novel neural antigens in children and adolescents with suspected autoimmune encephalitis, epilepsy, single seizures, or marked epileptiform activity in electroencephalography (EEG). Prospectively, 103 patients were recruited aged between 0 and 18 years and 104 controls. A panel of 35 autoantibodies against neural cell-surface and intracellular antigens was screened. Sixteen of 103 patients (15.5%) showed a positive result for 1 or more autoantibodies, compared to 6 of 104 controls (5.8%, P = .02). Neurochondrin was identified as a possible new target of autoantibodies in 3 patients within this cohort, but none in controls. The patients showed severe behavioral disturbances, memory and cognitive impairment, episodes of reduced responsiveness, but no seizures, and normal MRI. Clinical findings, course, and treatment response of these 3 patients are presented.
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Affiliation(s)
- Myriam Schumacher
- 1 Department of Child Neurology, Justus-Liebig University Gießen, Gießen, Germany
| | - Frank Risto Rommel
- 1 Department of Child Neurology, Justus-Liebig University Gießen, Gießen, Germany
| | - Borros Arneth
- 2 Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Justus-Liebig University Gießen, Gießen, Germany
| | - Harald Renz
- 2 Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Justus-Liebig University Gießen, Gießen, Germany
| | - Winfried Stöcker
- 3 Institute of Experimental Immunology, Euroimmun AG, Lübeck, Germany
| | - Anita Windhorst
- 4 Institute for Medical Informatics, Justus-Liebig-University, Giessen, Germany
| | - Andreas Hahn
- 1 Department of Child Neurology, Justus-Liebig University Gießen, Gießen, Germany
| | - Bernd Axel Neubauer
- 1 Department of Child Neurology, Justus-Liebig University Gießen, Gießen, Germany
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Wang H, Nong Y, Bazan F, Greengard P, Flajolet M. Norbin: A promising central nervous system regulator. Commun Integr Biol 2010; 3:487-90. [PMID: 21331221 DOI: 10.4161/cib.3.6.12844] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 06/29/2010] [Indexed: 11/19/2022] Open
Abstract
Norbin, a neurite-outgrowth promoting protein, has been found to interact with and regulate several membrane proteins, including metabotropic glutamate receptor 5 (mGluR5). The disruption of both Norbin alleles leads to early embryonic death between 3.5 and 6.5 day post coitus.1 Forebrain specific Norbin knockout (KO) mice are defective in synaptic plasticity,2 an interesting feature considering that Norbin was initially discovered in the context of chemical-induced long term potentiation (LTP),3 a form of synaptic plasticity extensively studied in the context of learning and memory.4 The behavioral phenotypes associated with Norbin conditional KO suggest reduced mGluR5 function. Because of its fundamental functions, Norbin is emerging as a key neuronal regulator. The aim of the present review is to summarize current knowledge about Norbin while emphasizing its role in the nervous system.
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Affiliation(s)
- Hong Wang
- Laboratory of Molecular and Cellular Neuroscience; The Rockefeller University; New York, NY USA
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Wang H, Westin L, Nong Y, Birnbaum S, Bendor J, Brismar H, Nestler E, Aperia A, Flajolet M, Greengard P. Norbin is an endogenous regulator of metabotropic glutamate receptor 5 signaling. Science 2010; 326:1554-7. [PMID: 20007903 DOI: 10.1126/science.1178496] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Metabotropic glutamate receptor 5 (mGluR5) is highly expressed in the mammalian central nervous system (CNS). It is involved in multiple physiological functions and is a target for treatment of various CNS disorders, including schizophrenia. We report that Norbin, a neuron-specific protein, physically interacts with mGluR5 in vivo, increases the cell surface localization of the receptor, and positively regulates mGluR5 signaling. Genetic deletion of Norbin attenuates mGluR5-dependent stable changes in synaptic function measured as long-term depression or long-term potentiation of synaptic transmission in the hippocampus. As with mGluR5 knockout mice or mice treated with mGluR5-selective antagonists, Norbin knockout mice showed a behavioral phenotype associated with a rodent model of schizophrenia, as indexed by alterations both in sensorimotor gating and psychotomimetic-induced locomotor activity.
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Affiliation(s)
- Hong Wang
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, NY 10065, USA
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