SGIP1 modulates kinetics and interactions of the cannabinoid receptor 1 and G protein‐coupled receptor kinase 3 signalosome. Issue 6 (11th January 2022)

• Record Type: Journal Article
• Authors: Gazdarica, Matej; Noda, Judith; Durydivka, Oleh; Novosadova, Vendula; Mackie, Ken; Pin, Jean‐Philippe; Prezeau, Laurent; Blahos, Jaroslav
• Is Part Of: Journal of neurochemistry. Volume 160:Issue 6(2022)
• Page Start: 625
• Page End: 642
• Publication Date: 2022-01-11
• Subjects: cannabinoid receptor 1 -- G protein‐coupled receptor kinase -- G protein‐coupled receptors -- phosphorylation -- SGIP1 -- β‐arrestin; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.15569
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Cannabinoid receptor 1 (CB1R), a G protein‐coupled receptor, plays a fundamental role in synaptic plasticity. Abnormal activity and deregulation of CB1R signaling result in a broad spectrum of pathological conditions. CB1R signaling is regulated by receptor desensitization including phosphorylation of residues within the intracellular C terminus by G protein‐coupled receptor kinases (GRKs) that may lead to endocytosis. Furthermore, CB1R signaling is regulated by the protein Src homology 3‐domain growth factor receptor‐bound 2‐like (SGIP1) that hinders receptor internalization, while enhancing CB1R association with β‐arrestin. It has been postulated that phosphorylation of two clusters of serine/threonine residues, 425 SMGDS 429 and 460 TMSVSTDTS 468, within the CB1R C‐tail controls dynamics of the association between receptor and its interaction partners involved in desensitization. Several molecular determinants of these events are still not well understood. We hypothesized that the dynamics of these interactions are modulated by SGIP1. Using a panel of CB1Rs mutated in the aforementioned serine and threonine residues, together with an array of Bioluminescence energy transfer‐based (BRET) sensors, we discovered that GRK3 forms complexes with Gβγ subunits of G proteins that largely independent of GRK3's interaction with CB1R. Furthermore, CB1R interacts only with activated GRK3. Interestingly, phosphorylation of two specific residues on CB1R triggers GRK3 dissociation from the desensitized receptor. SGIP1 increases the association of GRK3 with Gβγ subunits of G proteins, and with CB1R. Altogether, our data suggest that the CB1R signalosome complex is dynamically controlled by sequential phosphorylation of the receptor C‐tail and is also modified by SGIP1. Abstract : Cannabinoid receptor 1 C‐tail contains two serine/threonine clusters 456 SMGDS 429 and 460 TMSVSTDTS 468 that are important for desensitization of the activated receptor. We found that these motifs play distinct roles in the interaction of CB1R with GRK3 and β‐arrestin2. CB1R requires catalytically active GRK3 in order to interact with β‐arrestin2. Furthermore, SGIP1 profoundly modifies the signalosome of CB1R during desensitization. These findings provide new insight into the mechanism of signaling and desensitization of CB1R.