Gβ4γ1 as a modulator of M3 muscarinic receptor signalling and novel roles of Gβ1 subunits in the modulation of cellular signalling

• Published in: Cellular signalling 2015-08, Vol.27 (8), p.1597-1608
• Main Authors: Khan, Shahriar M., Min, Adam, Gora, Sarah, Houranieh, Geeda M., Campden, Rhiannon, Robitaille, Mélanie, Trieu, Phan, Pétrin, Darlaine, Jacobi, Ashley M., Behlke, Mark A., Angers, Stéphane, Hébert, Terence E.
• Format: Article
• Language: English
• Subjects: Binding Sites; Calcium Signaling; Carbachol - pharmacology; Cholinergic Agonists - pharmacology; Co-transcriptional regulation; Dose-Response Relationship, Drug; G protein-coupled receptors; G proteins; Gene Expression Regulation; GTP-Binding Protein beta Subunits - genetics; GTP-Binding Protein beta Subunits - metabolism; GTP-Binding Protein gamma Subunits - genetics; GTP-Binding Protein gamma Subunits - metabolism; Gβγ Signalling; HEK293 Cells; Humans; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Promoter Regions, Genetic; Protein Multimerization; Receptor, Muscarinic M3; Receptors, Muscarinic - drug effects; Receptors, Muscarinic - genetics; Receptors, Muscarinic - metabolism; RNA Interference; RNA interference screen; RNA, Messenger - metabolism; Signal Transduction - drug effects; Signalling specificity; Transcription, Genetic; Transfection
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/j.cellsig.2015.04.007

Much is known about the how Gβγ subunits regulate effectors in response to G protein-coupled receptor stimulation. However, there is still a lot we don't know about how specific combinations of Gβ and Gγ are wired into different signalling pathways. Here, using an siRNA screen for different Gβ and Gγ subunits, we examined an endogenous M3 muscarinic receptor signalling pathway in HEK 293 cells. We observed that Gβ4 subunits were critical for calcium signalling and a downstream surrogate measured as ERK1/2 MAP kinase activity. A number of Gγ subunits could partner with Gβ4 but the best coupling was seen via Gβ4γ1. Intriguingly, knocking down Gβ1 actually increased signalling through the M3-mAChR most likely via an increase in Gβ4 levels. We noted that Gβ1 occupies the promoter of Gβ4 and may participate in maturation of its mRNA. This highlights a new role for Gβγ signalling beyond their canonical roles in cellular signalling. •We identify specific Gβ and Gγ subunits involved in signalling downstream of M3-mAChR activation.•Gβ4γ1 is the key regulator of second messenger signalling downstream of M3-mAChRs.•Gβ1 plays a novel non-canonical role as a co-transcriptional regulator in GPCR signalling.