1. Phosphorylation patterns in the AT1R C-terminal tail specify distinct downstream signaling pathways.
- Author
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Gareri C, Pfeiffer CT, Jiang X, Paulo JA, Gygi SP, Pham U, Chundi A, Wingler LM, Staus DP, Stepniewski TM, Selent J, Lucero EY, Grogan A, Rajagopal S, and Rockman HA
- Subjects
- Phosphorylation, Humans, HEK293 Cells, Molecular Dynamics Simulation, Angiotensin II metabolism, Receptor, Angiotensin, Type 1 metabolism, Receptor, Angiotensin, Type 1 chemistry, Receptor, Angiotensin, Type 1 genetics, Signal Transduction, beta-Arrestins metabolism, beta-Arrestins genetics
- Abstract
Different ligands stabilize specific conformations of the angiotensin II type 1 receptor (AT1R) that direct distinct signaling cascades mediated by heterotrimeric G proteins or β-arrestin. These different active conformations are thought to engage distinct intracellular transducers because of differential phosphorylation patterns in the receptor C-terminal tail (the "barcode" hypothesis). Here, we identified the AT1R barcodes for the endogenous agonist AngII, which stimulates both G protein activation and β-arrestin recruitment, and for a synthetic biased agonist that only stimulates β-arrestin recruitment. The endogenous and β-arrestin-biased agonists induced two different ensembles of phosphorylation sites along the C-terminal tail. The phosphorylation of eight serine and threonine residues in the proximal and middle portions of the tail was required for full β-arrestin functionality, whereas phosphorylation of the serine and threonine residues in the distal portion of the tail had little influence on β-arrestin function. Similarly, molecular dynamics simulations showed that the proximal and middle clusters of phosphorylated residues were critical for stable β-arrestin-receptor interactions. These findings demonstrate that ligands that stabilize different receptor conformations induce different phosphorylation clusters in the C-terminal tail as barcodes to evoke distinct receptor-transducer engagement, receptor trafficking, and signaling.
- Published
- 2024
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