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The role of SGIP1 protein in the control of cannabinoid receptor
Gazdarica, Matej ; Blahoš, Jaroslav (advisor) ; Jakubík, Jan (referee) ; Novotný, Jiří (referee)
Two regions within the cannabinoid receptor 1 (CB1R) C-tail, 425 SMGDS429 and 460 TMSVSTDTS468 , contain clusters of serine and threonine residues that can be phosphorylated and collectively play an essential role in the desensitization and internalization of activated CB1R. First, I studied the role of phosphorylation of the aforementioned serine/threonine clusters in protein-protein interaction between CB1R and molecules relevant to the receptor desensitization and internalization using the Bioluminescence Resonance Energy Transfer method in tandem with pharmacological inhibitors. I show that CB1R interaction with G protein-coupled receptor kinases 3 (GRK3) and β-arrestin2 depends on distinct C-tail phosphorylation patterns. Furthermore, the activation of GRK3 is required for its interaction with CB1R. Second, I studied the impact of Src homology 3-domain growth factor receptor-bound 2-like endophilin interacting protein 1 (SGIP1) on the dynamics of CB1R signalosome and CB1R desensitization. SGIP1 altered CB1R interactions with GRK3, β-arrestin2 and GRK3-Gβγ coupling. Further, I characterize newly identified splice variants of SGIP1 and demonstrate that alternative splicing-based alterations in SGIP1 domains do not affect the inhibitory effect of SGIP1 on CB1R internalization. This study's...
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