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Regulation of cell surface GABA(B) receptors by trafficking mechanisms: contribution to synaptic plasticity and disease states

English title Regulation of cell surface GABA(B) receptors by trafficking mechanisms: contribution to synaptic plasticity and disease states
Applicant Benke Dietmar
Number 138382
Funding scheme Project funding
Research institution Institut für Pharmakologie und Toxikologie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Neurophysiology and Brain Research
Start/End 01.11.2011 - 31.10.2014
Approved amount 438'000.00
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All Disciplines (2)

Discipline
Neurophysiology and Brain Research
Pharmacology, Pharmacy

Keywords (6)

GABA(B) receptor; trafficking; endocytosis; exocytosis; neuron; chronic pain

Lay Summary (English)

Lead
Lay summary

Inhibitory neurotransmission ensures normal brain function by counteracting and integrating excitatory activity. The neurotransmitter GABA conveys the majority of neuronal inhibition, in part by activating the GABAB receptor. GABAB receptors are abundantly expressed throughout the nervous system and have been implicated in a variety of neurological disorders including epilepsy, spasticity, addiction, schizophrenia, depression, anxiety and chronic pain. There is considerable evidence that trafficking mechanisms dynamically define cell surface expression of receptors and as a result regulate and integrate signal transduction. Thus, it is not surprising that receptor trafficking is affected in disease states. Elucidating the mechanisms of receptor trafficking under normal and pathological conditions has therefore a significant potential to raise concepts for the development of novel therapeutic strategies. The intention of this project is to understand the trafficking mechanisms that regulate cell surface expression of GABAB receptors in neurons. To this end, we have shown that GABAB receptors are constitutively internalized and sorted to two distinct pathways: the majority of receptors are recycled back to the cell surface while a minor fraction is degraded in lysosomes. Our results indicate that GABAB receptor trafficking is a highly regulated process that enables the neuron to adjust their number of cell surface receptors to changing environmental conditions. In this project we aim at understanding how different aspects of GABAB receptor trafficking (exocytosis, endocytosis, recycling, sorting and degradation) are regulated by posttranslational modifications of the receptors (phosphorylation, ubiquitination) and GABAB receptor interacting proteins in healthy and diseased neurons. In addition, we intend to develop new methods for investigating receptor trafficking in vivo, which will enable us to analyze the trafficking mechanisms of GABAB receptors in animal models of diseases.

 

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
The positive allosteric GABAB receptor modulator rac-BHFF enhances baclofen-mediated analgesia in neuropathic mice
Zemoura K., Ralvenius W. T., Malherbe P., Benke D. (2016), The positive allosteric GABAB receptor modulator rac-BHFF enhances baclofen-mediated analgesia in neuropathic mice, in Neuropharmacology, 108, 172-178.
Ischemia-like oxygen and glucose deprivation mediates down-regulation of cell surface γ-aminobutyric acidB receptors via the endoplasmic reticulum (ER) stress-induced transcription factor CCAAT/enhancer-binding protein (C/EBP)-homologous protein (CHOP).
Maier Patrick J, Zemoura Khaled, Acuña Mario A, Yévenes Gonzalo E, Zeilhofer Hanns Ulrich, Benke Dietmar (2014), Ischemia-like oxygen and glucose deprivation mediates down-regulation of cell surface γ-aminobutyric acidB receptors via the endoplasmic reticulum (ER) stress-induced transcription factor CCAAT/enhancer-binding protein (C/EBP)-homologous protein (CHOP)., in The Journal of Biological Chemistry, 289(18), 12896-12907.
Proteasomal degradation of γ-aminobutyric acidB receptors is mediated by the interaction of the GABAB2 C terminus with the proteasomal ATPase Rtp6 and regulated by neuronal activity.
Zemoura Khaled, Benke Dietmar (2014), Proteasomal degradation of γ-aminobutyric acidB receptors is mediated by the interaction of the GABAB2 C terminus with the proteasomal ATPase Rtp6 and regulated by neuronal activity., in The Journal of Biological Chemistry, 289(11), 7738-7746.
Endoplasmic reticulum-associated degradation controls cell surface expression of γ-aminobutyric acid, type B receptors.
Zemoura Khaled, Schenkel Marisa, Acuña Mario A, Yévenes Gonzalo E, Zeilhofer Hanns Ulrich, Benke Dietmar (2013), Endoplasmic reticulum-associated degradation controls cell surface expression of γ-aminobutyric acid, type B receptors., in The Journal of biological chemistry, 288(48), 34897-34905.
GABAB receptor trafficking and interacting proteins: targets for the development of highly specific therapeutic strategies to treat neurological disorders?
Benke Dietmar (2013), GABAB receptor trafficking and interacting proteins: targets for the development of highly specific therapeutic strategies to treat neurological disorders?, in Biochemical pharmacology, 86(11), 1525-30.
Divorce of obligatory partners in pain: disruption of GABA(B) receptor heterodimers in neuralgia.
Benke Dietmar, Zeilhofer Hanns Ulrich (2012), Divorce of obligatory partners in pain: disruption of GABA(B) receptor heterodimers in neuralgia., in The EMBO journal, 31(15), 3234-6.
Modulation of cell surface GABA(B) receptors by desensitization, trafficking and regulated degradation.
Benke Dietmar, Zemoura Khaled, Maier Patrick J (2012), Modulation of cell surface GABA(B) receptors by desensitization, trafficking and regulated degradation., in World Journal of Biological Chemistry, 3(4), 61-72.

Collaboration

Group / person Country
Types of collaboration
Prof. H. U. Zeilhofer, Institute of Pharmacology and Toxicology, University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Prof. B. Weber, Institute of Pharmacology and Toxicology, University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Prof. J.-M. Fritschy, Institute of Pharmacology and Toxicology, University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Prof. Urs Gerber, Brain Research Institute, University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
SFN, Annual Meeting of the Society of Neuroscience 2014 Poster K63-linked ubiquitination of GABA(B1) sorts GABA(B) receptors to lysosomal degradation 15.11.2014 Washington DC, United States of America Zemoura Khaled;
24th Neuropharmacology Conference 2014: GABAergic Signaling in Health and Disease Talk given at a conference Neuronal activity controls cell surface expression of GABA(B) receptors via endoplasmic reticulum assosicated protein degradation 13.11.2014 Arlington, VA, United States of America Zemoura Khaled; Benke Dietmar;
ZNZ Symposium 2014 Poster K63-linked ubiquitination of GABA(B1) sorts GABA(B) receptors to lysosomal degradation 11.09.2014 Zürich, Switzerland Zemoura Khaled; Benke Dietmar;
Pharmacology & Toxicology Poster Day 2014 Poster The C-terminal domain of GABA(B1) contains an ERK II phosphorylation site potentially involved in ubiquitination and lysosomal degradation of GABA(B) receptors 08.09.2014 Zürich, Switzerland Benke Dietmar;
Pharmacology & Toxicology Poster Day 2014 Poster Neuronal activity controls cell surface trafficking of GABA(B) receptors via ERAD 08.09.2014 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
Pharmacology & Toxicology Poster Day 2014 Poster CaMKII dependent K63-linked polyubiquitination and lysosomal degradation of GABA(B) receptors 08.09.2014 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
Pharmacology & Toxicology Poster Day 2014 Talk given at a conference Regulation of GABA(B) receptor cell surface expression by degradation 08.09.2014 Zürich, Switzerland Zemoura Khaled;
EMBO Conference: Ubiquitin and Ubiquitin-like Proteins: from structure to function Poster Neuronal activity controls cell surface expression of GABA(B) receptors via ubiquitin andendoplasmic reticulum associated protein degradation 01.10.2013 Riva del Garda, Italy Zemoura Khaled;
ZNZ Symposium 2013 Poster Neuronal activity controls cell surface expression of GABA(B) receptorsvia endoplasmic reticulum associated protein degradation 13.09.2013 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
Pharmacology & Toxicology Poster day 2013 Poster Neuronal activity controls cell surface expression of GABA(B) receptors via endoplasmic reticulum associated protein degradation 20.08.2013 Zürich, Switzerland Zemoura Khaled; Benke Dietmar;
Phamacology & Toxicology Poster day 2013 Poster Ischemia-like oxygen and glucose deprivation mediates downregulation of cell-surface GABA(B) receptors via the ER stress-induced transcription factor CHOP 20.08.2013 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
Pharmacology & Toxicology Poster Day 2012 Poster Ischemia mediates the downregulation of cell surface GABA(B) receptors via the ER stress induced transcription factor CHOP 04.10.2012 Zürich, Switzerland Benke Dietmar; Maier Patrick;
Pharmacology & Toxicology Poster Day 2012 Poster Neuronal activity controls cell surface expression of GABA(B) receptors via endoplasmic reticulum associated protein degradation 04.10.2012 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
FENS Forum of European Neuroscience 2012 Poster Ischemia mediates downregulation of cell surface GABA(B) receptors via the ER stress-induced transcription factor CHOP 14.07.2012 Barcelona, Spain Maier Patrick; Benke Dietmar;
FENS Forum of European Neuroscience 2012 Poster Neuronal activity controls cell surface expression of GABA(B) receptors via endoplasmic reticulum associated protein degradation 14.07.2012 Barcelona, Spain Zemoura Khaled; Benke Dietmar;
ZNZ Symposium 2012 Poster Ischemia mediates the downregulation of cell surface GABA(B) receptors via the ER stress-induced transcription factor CHOP 14.06.2012 Zürich, Switzerland Benke Dietmar; Maier Patrick;
ZNZ Symposium 2012 Poster Neuronal activity controls cell surface expression of GABA(B) receptors via endoplasmic reticulum associated protein degradation 14.06.2012 Zürich, Switzerland Benke Dietmar; Zemoura Khaled;
SFN, Annual Meeting of the Society of Neuroscience 2011 Poster Stress-induced up-regulation of CHOP down-regulates cell surface GABA(B) receptors in neurons 12.11.2011 San Diego, United States of America Maier Patrick;
SFN, Annual Meeting of the Society of Neuroscience 2011 Poster GABA(B) receptors are targeted to proteasomal degradation via interaction with the AAA-ATPase SUG-1 12.11.2011 San Diego, United States of America Zemoura Khaled;


Associated projects

Number Title Start Funding scheme
156648 Regulation of cell surface GABA(B) receptors in cerebral ischemia: contribution to neuronal death and potential implications for novel therapeutic strategies 01.11.2014 Project funding
121963 Regulation of GABA(B) receptor cell surface expression by endocytosis under normal and pathophysiological conditions 01.11.2008 Project funding

Abstract

The metabotropic GABA(B) receptors mediate slow inhibitory neurotransmission and thereby regulate the excitability of neurons. They are abundantly expressed throughout the nervous system and have been implicated in several neurological disorders such as epilepsy, spasticity, addiction, schizophrenia, depression, anxiety and chronic pain. There is considerable evidence that trafficking mechanisms dynamically define cell surface expression of receptors and as a result regulate and integrate signal transduction. In addition, it is increasingly observed that receptor trafficking is affected in disease states. Studying the mechanisms of receptor trafficking under normal and pathological conditions has therefore a significant potential to raise concepts for the development of novel therapeutic strategies. The aim of this proposal is to understand the trafficking mechanisms that regulate cell surface expression of GABA(B) receptors in neurons derived from healthy and diseased animals. The research program is divided into four subprojects:In subproject 1 we intend to investigate how different aspects of GABA(B) receptor trafficking (endocytosis, recycling, sorting and degradation) are regulated by ubiquitination and how this is affected by neuronal activity. We expect that the results significantly advance our understanding how GABA(B) receptors contribute to neuronal plasticity.Subproject 2 addresses the physiological and pathological relevance of a mechanism (glutamate-induced down-regulation of GABA(B) receptors) that affects sorting of GABA(B) receptors. The results of this subproject will be pivotal to our understanding if and how GABA(B) receptor trafficking is regulated in the context of long-term potentiation, which is thought to underlie memory formation. Furthermore, we aim at analyzing the contribution of this mechanism to cell death as a consequence of ischemia. This has the potential to raise new ideas to interfere with glutamate-induced neuronal death.Subproject 3 tests the hypothesis that the interaction of GABA(B) receptors with a stress-induced protein (CHOP) down-regulates cell surface receptors and thereby contributes to the development or maintenance of diseases. This will be tested in an animal model of neuropathic pain and might provide the basis for the development of novel approaches to alleviate chronic pain states.In subproject 4 we intend to develop new methods that will enable us to investigate GABA(B) receptor trafficking in vivo. Currently, the analysis of receptor trafficking is predominantly restricted to cultured cells which prohibit the direct analysis of these mechanisms in animal models of diseases. We aim at developing two distinct methods: 1. a biochemical assay for the detection of cell surface receptors in eventually fixed brain slices with high spatial resolution and sensitivity at the single molecule level and 2. a method based on two-photon microscopy for real-time tracking of receptor dynamics in living brain slices and eventually living animals. The successful implementation of these new technologies is expected to advance the analysis of GABA(B) receptor trafficking to a further level.
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