Palmitoylation Regulates Intracellular Trafficking of β₂ Adrenergic Receptor/Arrestin/Phosphodiesterase 4D Complexes in Cardiomyocytes

Authors

Ruijie Liu, Grand Valley State UniversityFollow
Dayong Wang, University of Illinois at Urbana-Champaign
Qian Shi, University of Illinois at Urbana-Champaign
Qin Fu, University of Illinois at Urbana-Champaign
Steven Hizon, University of Illinois at Urbana-Champaign
Yang K. Xiang, University of Illinois at Urbana-Champaign

Keywords

Palmitoylation, Cardiomyocytes, Isoproterenol, Fluorescence resonance energy transfer, Phosphorylation, PKA signaling cascade, Immunoprecipitation, Cell membranes

Disciplines

Cardiovascular System

Abstract

β₂ adrenergic receptor (β₂AR) is a prototypical G-protein coupled receptor that stimulates the classic cAMP-protein kinase A (PKA) signaling pathway. Recent studies indicate that the cAMP-PKA activities are spatiotemporally regulated in part due to dynamic association of β₂AR with phosphodiesterase 4D (PDE4D), a group of cAMP degradation enzymes. Here, we demonstrate that in cardiomyocytes, palmitoylation of β₂AR, the covalent acylation of cysteine residue 341, plays a critical role in shaping subcellular cAMP-PKA activities in cardiomyocytes via regulating β₂AR association with arrestin/PDE4D. Replacing cysteine 341 on β₂AR with alanine (C341A) leads to an impaired binding to β arrestin 2. Surprisingly, the C341A mutant is able to internalize via an arrestin-independent pathway at saturated concentration of agonist stimulation; the internalization becomes caveolae-dependent and requires dynamin GTPase. However, the impaired binding to β arrestin 2 also leads to an impaired recruitment of PDE4D to the C341A mutant. Thus, the mutant C341A β₂AR is transported alone from the plasma membrane to the endosome without recruiting PDE4D. This alteration leads to an enhanced cytoplasmic cAMP signal for PKA activation under β₂AR stimulation. Functionally, Mutation of the C341 residue or inhibition of palmitoylation modification of β₂AR enhances the receptor-induced PKA activities in the cytoplasm and increases in myocyte contraction rate. Our data reveal a novel function of palmitoylation in shaping subcellular cAMP-PKA signaling in cardiomyocytes via modulating the recruitment of β arrestin 2-PDE4D complexes to the agonist-stimulated β₂AR.

Original Citation

Liu, R., Wang, D., Shi, Q., Fu, Q., Hizon, S., & Xiang, Y. K. (2012). Palmitoylation Regulates Intracellular Trafficking of β2 Adrenergic Receptor/Arrestin/Phosphodiesterase 4D Complexes in Cardiomyocytes. PLoS ONE, 7(8), 1–13. https://doi.org/10.1371/journal.pone.0042658

ScholarWorks Citation

Liu, Ruijie; Wang, Dayong; Shi, Qian; Fu, Qin; Hizon, Steven; and Xiang, Yang K., "Palmitoylation Regulates Intracellular Trafficking of β₂ Adrenergic Receptor/Arrestin/Phosphodiesterase 4D Complexes in Cardiomyocytes" (2012). Peer Reviewed Articles. 34.
https://scholarworks.gvsu.edu/bms_articles/34