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J Mol Cell Cardiol. 2013 Sep;62:8-17. doi: 10.1016/j.yjmcc.2013.04.025. Epub 2013 May 2.

Anti-hypertrophic and anti-oxidant effect of beta3-adrenergic stimulation in myocytes requires differential neuronal NOS phosphorylation.

Author information

1
Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Abstract

RATIONALE:

Stimulation of β3-adrenoreceptors (β3-AR) blunts contractility and improves chronic left ventricular function in hypertrophied and failing hearts in a neuronal nitric oxide synthase (nNOS) dependent manner. nNOS can be regulated by post-translational modification of stimulatory phosphorylation residue Ser1412 and inhibitory residue Ser847. However, the role of phosphorylation of these residues in cardiomyocytes and β3-AR protective signaling has yet to be explored.

OBJECTIVE:

We tested the hypothesis that β3-AR regulation of myocyte stress requires changes in nNOS activation mediated by differential nNOS phosphorylation.

METHODS AND RESULTS:

Endothelin (ET-1) or norepinephrine induced hypertrophy in rat neonatal ventricular cardiomyocytes (NRVMs) was accompanied by increased β3-AR gene expression. Co-administration of the β3-AR agonist BRL-37433 (BRL) reduced cell size and reactive oxygen species (ROS) generation, while augmenting NOS activity. BRL-dependent augmentation of NOS activity and ROS suppression due to NE were blocked by inhibiting nNOS (L-VNIO). BRL augmented nNOS phosphorylation at Ser1412 and dephosphorylation at Ser847. Cells expressing constitutively dephosphorylated Ser1412A or phosphorylated Ser847D nNOS mutants displayed reduced nNOS activity and a lack of BRL modulation. BRL also failed to depress ROS from NE in cells with nNOS-Ser847D. Inhibiting Akt decreased BRL-induced nNOS-Ser1412 phosphorylation and NOS activation, whereas Gi/o blockade blocked BRL-regulation of both post-translational modifications, preventing enhancement of NOS activity and ROS reduction. BRL resulted in near complete dephosphorylation of Ser847 and a moderate rise in Ser1412 phosphorylation in mouse myocardium exposed to chronic pressure-overload.

CONCLUSION:

β3-AR regulates myocardial NOS activity and ROS via activation of nNOS involving reciprocal changes in phosphorylation at two regulatory sites. These data identify a novel and potent anti-oxidant and anti-hypertrophic pathway due to nNOS post-translational modification that is coupled to β3-AR receptor stimulation.

KEYWORDS:

Beta3-adrenergic receptors; Heart failure; Hypertrophy; Neuronal nitric oxide synthase; Reactive oxygen species

PMID:
23643588
PMCID:
PMC4041152
DOI:
10.1016/j.yjmcc.2013.04.025
[Indexed for MEDLINE]
Free PMC Article
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