Mono-ADP-ribosylation of the G protein betagamma dimer is modulated by hormones and inhibited by Arf6

• Published in: The Journal of biological chemistry 2011-02, Vol.286 (8), p.5995
• Main Authors: Dani, Nadia, Mayo, Emilia, Stilla, Annalisa, Marchegiani, Adriano, Di Paola, Simone, Corda, Daniela, Di Girolamo, Maria
• Format: Article
• Language: English
• Subjects: Adenosine Diphosphate Ribose - genetics; Adenosine Diphosphate Ribose - metabolism; ADP Ribose Transferases - antagonists & inhibitors; ADP Ribose Transferases - genetics; ADP Ribose Transferases - metabolism; ADP-Ribosylation Factors - genetics; ADP-Ribosylation Factors - metabolism; Animals; Cattle; CHO Cells; Cricetinae; Cricetulus; GTP-Binding Protein beta Subunits - genetics; GTP-Binding Protein beta Subunits - metabolism; GTP-Binding Protein gamma Subunits - genetics; GTP-Binding Protein gamma Subunits - metabolism; Hormones - metabolism; Hormones - pharmacology; Humans; Protein Processing, Post-Translational - drug effects; Protein Processing, Post-Translational - physiology; Receptors, LHRH - genetics; Receptors, LHRH - metabolism
• ISSN: 1083-351X
• DOI: 10.1074/jbc.M110.112466

Mono-ADP-ribosylation is a reversible post-translational modification that can modulate the functions of target proteins. We have previously demonstrated that the β subunit of heterotrimeric G proteins is endogenously mono-ADP-ribosylated, and once modified, the βγ dimer is inactive toward its effector enzymes. To better understand the physiological relevance of this post-translational modification, we have studied its hormonal regulation. Here, we report that Gβ subunit mono-ADP-ribosylation is differentially modulated by G protein-coupled receptors. In intact cells, hormone stimulation of the thrombin receptor induces Gβ subunit mono-ADP-ribosylation, which can affect G protein signaling. Conversely, hormone stimulation of the gonadotropin-releasing hormone receptor (GnRHR) inhibits Gβ subunit mono-ADP-ribosylation. We also provide the first demonstration that activation of the GnRHR can activate the ADP-ribosylation factor Arf6, which in turn inhibits Gβ subunit mono-ADP-ribosylation. Indeed, removal of Arf6 from purified plasma membranes results in loss of GnRHR-mediated inhibition of Gβ subunit mono-ADP-ribosylation, which is fully restored by re-addition of purified, myristoylated Arf6. We show that Arf6 acts as a competitive inhibitor of the endogenous ADP-ribosyltransferase and is itself modified by this enzyme. These data provide further understanding of the mechanisms that regulate endogenous ADP-ribosylation of the Gβ subunit, and they demonstrate a novel role for Arf6 in hormone regulation of Gβ subunit mono-ADP-ribosylation.