Subcellular distribution of GABAB receptor homo- and hetero-dimers

Villemure, Josée-France; Adam, Lynda; Bevan, Nicola; Gearing, Katy; Chénier, Sébastien; Bouvier, Michel

doi:10.1042/bj20041435

Cited by 49 publications

(48 citation statements)

References 39 publications

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“…This discrepancy may represent a weak interaction between the extracellular regions of GBR1 and GBR2 and may indicate the importance of the intracellular coiled-coil region for the full receptor activity. In the density gradient centrifugation we also identified homo-oligomerization states of extracellular regions of GBR1 and GBR2 (25). Intriguingly, the oligomerization manner of GBR1-ECR3 was apparently different from that of GBR2-ECR.…”

Section: Determination Of the C-terminal End Of Gbr1 Extracellularmentioning

confidence: 79%

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Nomura

Suzuki²,

Kakizuka

et al. 2008

Journal of Biological Chemistry

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The ␥-aminobutyric acid, type B (GABA B ) receptor is a heterodimeric receptor consisting of two complementary subunits, GABA B1 receptor (GBR1) and GABA B2 receptor (GBR2). GBR1 is responsible for GABA binding, whereas GBR2 is considered to perform a critical role in signal transduction toward downstream targets. Therefore, precise communication between GBR1 and GBR2 is thought to be essential for the proper signal transduction process. However, biochemical data describing the interaction of the two subunits, especially for the extracellular regions, are not sufficient. Thus we began by developing a protein expression system of the soluble extracellular regions. One of the soluble recombinant GBR1 proteins exhibited a ligand binding ability, which is similar to that of the full-length GBR1, and thus the ligand-binding domain was determined. Direct interaction between GBR1 and GBR2 extracellular soluble fragments was confirmed by co-expression followed by affinity column chromatography and a sucrose density gradient sedimentation. In addition, we also found homo-oligomeric states of these soluble extracellular regions. The interaction between the two soluble extracellular regions caused the enhancement of the agonist affinity for GBR1 as previously reported in a cell-based assay. These results not only open the way to future structural studies but also highlight the role of the interaction between the extracellular regions, which controls agonist affinity to the heterodimeric receptor.

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Section: Determination Of the C-terminal End Of Gbr1 Extracellularmentioning

confidence: 79%

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Nomura

Suzuki²,

Kakizuka

et al. 2008

Journal of Biological Chemistry

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“…However, one important distinction is that either SD can fulfill the targeting role, which differs from their receptor stabilizing role, where both are an absolute requirement. It is possible that the SDs may interact across the subunits in the R1aR2 heteromer enabling SD1-SD2 to stabilize larger oligomeric complexes (28,29) on the cell surface.…”

Section: Discussionmentioning

confidence: 99%

Sushi domains confer distinct trafficking profiles on GABA _B receptors

Hannan

Wilkins

Smart

2012

Proc. Natl. Acad. Sci. U.S.A.

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GABA B receptors mediate slow inhibitory neurotransmission in the brain and feature during excitatory synaptic plasticity, as well as various neurological conditions. These receptors are obligate heterodimers composed of GABA B R1 and R2 subunits. The two predominant R1 isoforms differ by the presence of two complement control protein modules or Sushi domains (SDs) in the N terminus of R1a. By using live imaging, with an α-bungarotoxin-binding site (BBS) and fluorophore-linked bungarotoxin, we studied how R2 stabilizes R1b subunits at the cell surface. Heterodimerization with R2 reduced the rate of internalization of R1b, compared with R1b homomers. However, R1aR2 heteromers exhibited increased cell surface stability compared with R1bR2 receptors in hippocampal neurons, suggesting that for receptors containing the R1a subunit, the SDs play an additional role in the surface stability of GABA B receptors. Both SDs were necessary to increase the stability of R1aR2 because single deletions caused the receptors to be internalized at the same rate and extent as R1bR2 receptors. Consistent with these findings, a chimera formed from the metabotropic glutamate receptor (mGluR)2 and the SDs from R1a increased the surface stability of mGluR2. These results suggest a role for SDs in stabilizing cell surface receptors that could impart different pre-and postsynaptic trafficking itineraries on GABA B receptors, thereby contributing to their physiological and pathological roles. underlying slow GABA-mediated inhibitory neurotransmission (1) that regulates neuronal excitability (2-4). These receptors are increasingly considered as potential therapeutic targets for a range of diseases, including epilepsy, schizophrenia, anxiety, depression, and substance abuse (1, 5). Functional GABA B receptors are heteromers formed from GABA B R1 subunits containing the agonist binding domain (6) and R2 subunits that link to G protein signaling (7,8).To date, just one isoform of the R2 subunit has been reported (9, 10), whereas several isoforms of the R1 subunit exist [R1a, R1b, R1c, R1e, R1j (1)]. Among these, R1a and R1b predominate in the central nervous system (CNS), and their expression arises by the use of different promoters (11) of the GABBR1 gene. R1a subunits contain 143 aa forming two Sushi domains (SDs) in the N terminus, which are also known as complement control proteins or short consensus repeats (12). These SDs are absent in R1b being replaced by 18 unique amino acids.Heteromers formed from R1aR2 and R1bR2 are thought to play distinct roles in neurotransmission (13-18), with R1aR2 contributing to presynaptic heteroreceptors to inhibit neurotransmitter release, although both R1aR2 and R1bR2 populate postsynaptic membranes to dampen excitability. These heteromeric subtypes exhibit different subcellular compartmentalization with the SDs acting as an axonal-targeting sequence to deliver R1aR2 more efficiently to axons compared with R1bR2 (19). This would, in part, explain the differential pre-and postsynaptic signaling properties o...

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“…To this end, PCR fragments containing the entire coding sequences of the human MC3R or MC4R were subcloned into the pcDNA4 vector (Invitrogen) in a way that fused the anti-Xpress peptide to the 5Ј-end of the MCR. pcDNA3.1-GABA BR2 -Rluc, pcDNA3.1-␤-arrestin-2-YFP, pcDNA3.1-GABA-BR2 -YFP, or pcDNA3.1-␤-arrestin-2-Rluc constructs were kindly provided by Dr. Bouvier (Montréal, Canada) and are described elsewhere (23,24). The pAD-CREFluc plasmid was kindly provided by Dr. Himmler, Bender GmbH (Vienna, Austria), and the pcDNA3.1-␤-arrestin-YFP construct was kindly provided from the laboratory of Dr. Lohse (Würzburg, Germany).…”

Section: Methodsmentioning

confidence: 99%

The Natural Inverse Agonist Agouti-related Protein Induces Arrestin-mediated Endocytosis of Melanocortin-3 and -4 Receptors

Breit

Wolff

Kalwa

et al. 2006

Journal of Biological Chemistry

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Agouti-related protein (Agrp), one of the two naturally occurring inverse agonists known to inhibit G protein-coupled receptor activity, regulates energy expenditure by decreasing basal and blocking agonist-promoted melanocortin receptor (MCR) signaling. Here we report that, in addition to its inverse agonistic activities, Agrp exhibits agonistic properties on the endocytosis pathway of melanocortin receptors. Sustained exposure of human embryonic kidney 293 cells to Agrp induced endocytosis of the MC3R or the MC4R. The extent and kinetics of Agrppromoted MCR endocytosis were similar to the endocytosis induced by melanocortins. Using the bioluminescence resonance energy transfer technique, we further showed that after binding of Agrp both MCRs interacted with ␤-arrestins. In line with this observation, in COS-7 cells co-expression of ␤-arrestins enhanced Agrp-induced MCR endocytosis, whereas in human embryonic kidney 293 cells co-transfection of ␤-arrestin-specific small interference RNAs diminished Agrp-promoted endocytosis. This new regulatory mechanism was likewise detectable in a cell line derived from murine hypothalamic neurons endogenously expressing MC4R, pointing to the physiological relevance of Agrp-promoted receptor endocytosis. In conclusion, we demonstrated that Agrp does not solely act by directly blocking MCR signaling but also by reducing the amount of MCR molecules accessible to melanocortins at the cell surface. This ␤-arrestin-dependent mechanism reveals a new aspect of MCR signaling in particular and refines the concept of G protein-coupled receptor antagonism in general.

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Subcellular distribution of GABAB receptor homo- and hetero-dimers

Cited by 49 publications

References 39 publications

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Sushi domains confer distinct trafficking profiles on GABA _B receptors

The Natural Inverse Agonist Agouti-related Protein Induces Arrestin-mediated Endocytosis of Melanocortin-3 and -4 Receptors

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Subcellular distribution of GABAB receptor homo- and hetero-dimers

Cited by 49 publications

References 39 publications

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Direct Detection of the Interaction between Recombinant Soluble Extracellular Regions in the Heterodimeric Metabotropic γ-Aminobutyric Acid Receptor

Sushi domains confer distinct trafficking profiles on GABA B receptors

The Natural Inverse Agonist Agouti-related Protein Induces Arrestin-mediated Endocytosis of Melanocortin-3 and -4 Receptors

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Sushi domains confer distinct trafficking profiles on GABA _B receptors