Agonist-induced formation of unproductive receptor-G
| Autor: | Najeah, Okashah, Shane C, Wright, Kouki, Kawakami, Signe, Mathiasen, Joris, Zhou, Sumin, Lu, Jonathan A, Javitch, Asuka, Inoue, Michel, Bouvier, Nevin A, Lambert |
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| Rok vydání: | 2020 |
| Předmět: |
Bioluminescence Resonance Energy Transfer Techniques
Pharmacology Receptors Vasopressin Vasopressins arrestin fungi Biological Sciences Ligands GTP-Binding Protein alpha Subunits G12-G13 ternary complex Receptors G-Protein-Coupled HEK293 Cells GPCR GTP-Binding Proteins Cyclic AMP GTP-Binding Protein alpha Subunits Gs Humans G protein-coupled receptor beta-Arrestins Protein Binding Signal Transduction |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 |
| Popis: | Significance G protein-coupled receptors (GPCRs) are targeted by a large fraction of approved drugs and regulate many important cellular processes. Association of GPCRs with heterotrimeric G proteins in response to agonist activation is thought to invariably lead to G protein activation. We find instead that G12 heterotrimers can associate with agonist-bound receptors in a manner that does not lead to activation. These unproductive agonist–receptor-G protein ternary complexes sequester G12 heterotrimers and thus inhibit rather than support G12 signaling. These findings reveal a mechanism whereby agonist activation of GPCRs can inhibit as well as promote G protein signaling. G proteins are activated when they associate with G protein-coupled receptors (GPCRs), often in response to agonist-mediated receptor activation. It is generally thought that agonist-induced receptor-G protein association necessarily promotes G protein activation and, conversely, that activated GPCRs do not interact with G proteins that they do not activate. Here we show that GPCRs can form agonist-dependent complexes with G proteins that they do not activate. Using cell-based bioluminescence resonance energy transfer (BRET) and luminescence assays we find that vasopressin V2 receptors (V2R) associate with both Gs and G12 heterotrimers when stimulated with the agonist arginine vasopressin (AVP). However, unlike V2R-Gs complexes, V2R-G12 complexes are not destabilized by guanine nucleotides and do not promote G12 activation. Activating V2R does not lead to signaling responses downstream of G12 activation, but instead inhibits basal G12-mediated signaling, presumably by sequestering G12 heterotrimers. Overexpressing G12 inhibits G protein receptor kinase (GRK) and arrestin recruitment to V2R and receptor internalization. Formyl peptide (FPR1 and FPR2) and Smoothened (Smo) receptors also form complexes with G12 that are insensitive to nucleotides, suggesting that unproductive GPCR-G12 complexes are not unique to V2R. These results indicate that agonist-dependent receptor-G protein association does not always lead to G protein activation and may in fact inhibit G protein activation. |
| Databáze: | OpenAIRE |
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