Tandem Subunits Effectively Constrain GABA<sub>A</sub>Receptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABA<sub>A</sub>Receptor-Associated Protein

Boileau, Andrew J.; Pearce, Robert A.; Czajkowski, Cynthia

doi:10.1523/jneurosci.3751-05.2005

Cited by 47 publications

(63 citation statements)

References 55 publications

(62 reference statements)

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“…Furthermore, the single channel conductance was significantly higher in L929 cells coexpressing ␣1␤2␥2S subunits with GABARAP than without (Everitt et al, 2004), showing high conductance states similar to those observed in native receptors (Fatima-Shad and Barry, 1992;Curmi et al, 1993;Birnir et al, 1994Birnir et al, , 2001. Recently, we and others reported that overexpression of GABARAP increased the cell-surface number of GABA A receptors (Leil et al, 2004;Boileau et al, 2005;Chen et al, 2005). Immunostaining microscopy showed that GABARAP colocalized with intracellular vesicular GABA A receptors and to some extent with plasma membrane GABA A receptors but not with synaptically localized GABA A receptors and gephyrin (Kneussel et al, 2000;Kittler et al, 2001;Leil et al, 2004).…”

Section: Introductionsupporting

confidence: 53%

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C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

Chen¹,

Chang²,

Leil³

et al. 2007

Journal of Neuroscience

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We investigated the ubiquitin-like modification of GABA A receptor-associated protein (GABARAP) and its function. A fusion protein of GABARAP with v5 in the N terminus and myc in the C terminus was expressed in rat cultured hippocampal neurons and PC12 cells. Western blotting with antibodies to v5 and myc revealed that the C terminus of GABARAP was cleaved off. Cleavage was blocked by mutating the C-terminal Gly116 to Ala, suggesting that G116 is required for the processing. Unlike ubiquitin, GABARAP was not incorporated covalently into higher-molecular-weight protein complexes. Nor was GABARAP degraded by ubiquitinylation through the proteasome, although GABARAP formed noncovalent dimers. Immunofluorescent confocal microscopy demonstrated that recombinantly expressed GABARAP was diffusely localized in PC12 cells. However, prevention of C-terminal processing in the mutant GABARAP G116A resulted in redistribution to the Golgi. In neurons, punctate cytoplasmic staining of GABARAP was seen in soma and processes, whereas GABARAP G116A was limited to soma. Compared with wild-type GABARAP, the colocalization and interaction of GABARAP G116A with GABA A receptors were significantly reduced, resulting in a reduction in expression of receptors in the plasma membrane. When ␣1␤2␥2S-containing GABA A receptors were expressed in oocytes, the increased surface expression of GABA A receptors, as shown by increased GABA currents and surface-accessible GABA A receptor subunit polypeptides resulting from GABARAP coexpression, was prevented by mutation G116A. In addition, the distribution of NSF (N-ethylmaleimide-sensitive factor) was affected in GABARAP G116A -expressing neurons. These results suggest that glycine 116 is required for C-terminal processing of GABARAP and that processing is essential for the localization of GABARAP and its functions as a trafficking protein.

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Section: Introductionsupporting

confidence: 53%

“…GABARAP was shown previously to increase the cell-surface expression of GABA A receptors (Leil et al, 2004;Boileau et al, 2005;Chen et al, 2005). Applying GABARAP IgG from StiffPerson Syndrome patients decreased the surface GABA A receptors in cultured hippocampal neurons (Raju et al, 2006).…”

Section: Discussionmentioning

confidence: 93%

C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

Chen¹,

Chang²,

Leil³

et al. 2007

Journal of Neuroscience

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“…In contrast, in αβ-expressing receptors, desensitization was more significantly enhanced when F was present in the β subunit. There continues to be some debate regarding the stoichiometry of αβ-expressing receptors [1,2,5,7,11]. Although not definitive, our studies support the presence of 3 β and 2 α subunits in these receptors, since desensitization was more significantly enhanced in α1β2(T6′F) receptors compared to α1(T6′F)β2 receptors.…”

Section: Discussionmentioning

confidence: 42%

Stoichiometric analysis of the TM2 6′ phenylalanine mutation on desensitization in α1β2 and α1β2γ2 GABAA receptors

Gonzales

Bell-Horner

Dibas

et al. 2008

Neuroscience Letters

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SummaryThe presence of phenylalanine (F) at the 6′ position of transmembrane domain 2 (TM2) in the α4 subunit of α4β2 nicotinic receptors enhances desensitization. As the GABA A receptor affords the ability to study the influence of as few as one and as many as five Fs at this position, we have used it to investigate potential subunit-and stoichiometry-dependent effects of the TM2 6′F mutation on desensitization. Whereas the presence of one F at this position decreased extent of desensitization, desensitization was increased in all configurations that included two or more Fs at the TM2 6′ position; desensitization was particularly rapid with 3 or 4 F residues present. Our results demonstrate the ability of phenylalanine residues at the TM2 6′ position to modulate desensitization is likely conserved in the cys-loop family of ligand-gated ion channels. Moreover, our findings demonstrate both stoichiometric-and subunit-dependent effects of the ability of this mutation to regulate desensitization in GABA A receptors.

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“…GABARAP, a 14-kDa polypeptide, originally was identified as an intracellular protein with sequence similarity to light chain 3 of microtubule-associated proteins 1A and 1B (18). GABARAP can interact with the ␥2 subunits of GABA A -Rs (35) and facilitate the surface presentation of GABA A -Rs (2,4).…”

Section: Discussionmentioning

confidence: 99%

Borna Disease Virus P Protein Affects Neural Transmission through Interactions with Gamma-Aminobutyric Acid Receptor-Associated Protein

Peng

Yan

Zhu

et al. 2008

J Virol

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Borna disease virus (BDV) is one of the infectious agents that causes diseases of the central nervous systemin a wide range of vertebrate species and, perhaps, in humans. The phosphoprotein (P) of BDV, an essential cofactor of virus RNA-dependent RNA polymerase, is required for virus replication. In this study, we identified the gamma-aminobutyric acid receptor-associated protein (GABARAP) with functions in neurobiology as one of the viral P protein-interacting cellular factors by using an approach of phage display-based protein-protein interaction analysis. Direct binding between GABARAP and P protein was confirmed by coimmunoprecipitation, protein pull-down, and mammalian two-hybrid analyses. GABARAP originally was identified as a linker between the gamma-aminobutyric acid receptor (GABAR) and the microtubule to regulate receptor trafficking and plays important roles in the regulation of the inhibitory neural transmitter gamma-aminobutyric acid (GABA). We showed that GABARAP colocalizes with P protein in the cells infected with BDV or transfected with the P gene, which resulted in shifting the localization of GABARAP from the cytosol to the nucleus. We further demonstrated that P protein blocks the trafficking of GABAR, a principal GABA-gated ion channel that plays important roles in neural transmission, to the surface of cells infected with BDV or transfected with the P gene. We proposed that during BDV infection, P protein binds to GABARAP, shifts the distribution of GABARAP from the cytoplasm to the nucleus, and disrupts the trafficking of GABARs to the cell membranes, which may result in the inhibition of GABA-induced currents and in the enhancement of hyperactivity and anxiety.Borna disease virus (BDV), a nonsegmental negative-strand RNA virus, belongs to the Bornaviridae family and is characterized by low productivity, neurotropism, and the nuclear localization of transcription and replication (12,33). BDV was reported to cause diseases of the central nervous system (CNS) in sheep and horses originally and then in a wide range of other vertebrate species (25). Epidemiological studies have shown that a higher prevalence of BDV infection was found in psychiatric patients than in controls, indicating that BDV is a potential human pathogen related to psychiatric diseases (1, 19). In contrast, some reports suggested that BDV does not play significant roles in human health (9, 36).One of the most prominent features of BDV infection is the heavy inflammatory reaction in the CNS and the rare degeneration of neurons in naturally infected hosts (25). In experimentally infected rats, the histopathology of the CNS is dependent on the immune status of the host at the time of inoculation, the genetic background, and the route of infection (33). The inoculation of immunocompetent adult rats with BDV results in marked immune-mediated meningoencephalitis consistent with the classical Borna disease. In the process of the persistent infection of BDV in adult rats, the degeneration of the neurons is observed. In contrast, i...

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Tandem Subunits Effectively Constrain GABA_AReceptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABA_AReceptor-Associated Protein

Cited by 47 publications

References 55 publications

C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

Stoichiometric analysis of the TM2 6′ phenylalanine mutation on desensitization in α1β2 and α1β2γ2 GABAA receptors

Borna Disease Virus P Protein Affects Neural Transmission through Interactions with Gamma-Aminobutyric Acid Receptor-Associated Protein

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Tandem Subunits Effectively Constrain GABAAReceptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABAAReceptor-Associated Protein

Cited by 47 publications

References 55 publications

C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

C-Terminal Modification Is Required for GABARAP-Mediated GABAA Receptor Trafficking

Stoichiometric analysis of the TM2 6′ phenylalanine mutation on desensitization in α1β2 and α1β2γ2 GABAA receptors

Borna Disease Virus P Protein Affects Neural Transmission through Interactions with Gamma-Aminobutyric Acid Receptor-Associated Protein

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Tandem Subunits Effectively Constrain GABA_AReceptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABA_AReceptor-Associated Protein