Enhanced β2AR phosphorylation by GRK leads to Gi-biased signaling, which contributes to the pathogenesis of heart failure and cardiac maladaptive remodeling in response to pressure overload.
Enhanced beta2AR phosphorylation by GRK leads to Gi-biased signaling, which is a primary mechanism linking GRK2 upregulation to maladaptive cardiac remodeling and heart failure.
RATIONALE: Phosphorylation of β(2)-adrenergic receptor (β(2)AR) by a family of serine/threonine kinases known as G protein-coupled receptor kinase (GRK) and protein kinase A (PKA) is a critical determinant of cardiac function. Upregulation of G protein-coupled receptor kinase 2 (GRK2) is a well-established causal factor of heart failure, but the underlying mechanism is poorly understood. OBJECTIVE: We sought to determine the relative contribution of PKA- and GRK-mediated phosphorylation of β(2)AR to the receptor coupling to G(i) signaling that attenuates cardiac reserve and contributes to the pathogenesis of heart failure in response to pressure overload. METHODS AND RESULTS: Overexpression of GRK2 led to a G(i)-dependent decrease of contractile response to βAR stimulation in cultured mouse cardiomyocytes and in vivo. Importantly, cardiac-specific transgenic overexpression of a mutant β(2)AR lacking PKA phosphorylation sites (PKA-TG) but not the wild-type β(2)AR (WT-TG) or a mutant β(2)AR lacking GRK sites (GRK-TG) led to exaggerated cardiac response to pressure overload, as manifested by markedly exacerbated cardiac maladaptive remodeling and failure and early mortality. Furthermore, inhibition of G(i) signaling with pertussis toxin restores cardiac function in heart failure associated with increased β(2)AR to G(i) coupling induced by removing PKA phosphorylation of the receptor and in GRK2 transgenic mice, indicating that enhanced phosphorylation of β(2)AR by GRK and resultant increase in G(i)-biased β(2)AR signaling play an important role in the development of heart failure. CONCLUSIONS: Our data show that enhanced β(2)AR phosphorylation by GRK, in addition to PKA, leads the receptor to G(i)-biased signaling, which, in turn, contributes to the pathogenesis of heart failure, marking G(i)-biased β(2)AR signaling as a primary event linking upregulation of GRK to cardiac maladaptive remodeling, failure and cardiodepression.
Zhu et al. (Fri,) conducted a other in Heart failure. GRK2 overexpression and mutant β2AR lacking PKA phosphorylation sites vs. Wild-type β2AR or mutant β2AR lacking GRK sites was evaluated on Cardiac response to pressure overload (remodeling, failure, and mortality). Enhanced β2AR phosphorylation by GRK leads to Gi-biased signaling, which contributes to the pathogenesis of heart failure and cardiac maladaptive remodeling in response to pressure overload.