Endoplasmic Reticulum-associated Degradation Controls Cell Surface Expression of γ-Aminobutyric Acid, Type B Receptors
| Autor: | Khaled Zemoura, Marisa Schenkel, Hanns Ulrich Zeilhofer, Dietmar Benke, Gonzalo E. Yévenes, Mario A. Acuña |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Proteasome Endopeptidase Complex
Immune receptor Biology GABAB receptor Endoplasmic-reticulum-associated protein degradation Endoplasmic Reticulum Biochemistry gamma-Aminobutyric acid 03 medical and health sciences 0302 clinical medicine Neurobiology Cell surface receptor medicine Animals Humans Rats Wistar Receptor Molecular Biology gamma-Aminobutyric Acid 030304 developmental biology Neurons 0303 health sciences Ubiquitin GABAA receptor Ubiquitination Endoplasmic Reticulum-Associated Degradation Cell Biology Rats Cell biology HEK293 Cells Metabotropic receptor Gene Expression Regulation Receptors GABA-B nervous system Proteolysis 030217 neurology & neurosurgery medicine.drug |
| Zdroj: | The Journal of biological chemistry |
| ISSN: | 0021-9258 |
| Popis: | Metabotropic GABAB receptors are crucial for controlling the excitability of neurons by mediating slow inhibition in the CNS. The strength of receptor signaling depends on the number of cell surface receptors, which is thought to be regulated by trafficking and degradation mechanisms. Although the mechanisms of GABAB receptor trafficking are studied to some extent, it is currently unclear whether receptor degradation actively controls the number of GABAB receptors available for signaling. Here we tested the hypothesis that proteasomal degradation contributes to the regulation of GABAB receptor expression levels. Blocking proteasomal activity in cultured cortical neurons considerably enhanced total and cell surface expression of GABAB receptors, indicating the constitutive degradation of the receptors by proteasomes. Proteasomal degradation required Lys(48)-linked polyubiquitination of lysines 767/771 in the C-terminal domain of the GABAB2 subunit. Inactivation of these ubiquitination sites increased receptor levels and GABAB receptor signaling in neurons. Proteasomal degradation was mediated by endoplasmic reticulum-associated degradation (ERAD) as shown by the accumulation of receptors in the endoplasmic reticulum upon inhibition of proteasomes, by the increase of receptor levels, as well as receptor signaling upon blocking ERAD function, and by the interaction of GABAB receptors with the essential ERAD components Hrd1 and p97. In conclusion, the data support a model in which the fraction of GABAB receptors available for plasma membrane trafficking is regulated by degradation via the ERAD machinery. Thus, modulation of ERAD activity by changes in physiological conditions may represent a mechanism to adjust receptor numbers and thereby signaling strength. |
| Databáze: | OpenAIRE |
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