Beta 3 adrenoreceptors protect from hypertrophic remodelling through AMP-activated protein kinase and autophagy.
Abstract
The abundance of beta 3-adrenergic receptors (β3-ARs) is upregulated in diseased human myocardium. We previously showed that cardiac-specific expression of β3-AR inhibits the hypertrophic response to neurohormonal stimulation. Here, we further analysed signalling pathways involved in the anti-hypertrophic effect of β3-AR. In vitro hypertrophic responses to phenylephrine (PE) were analysed in neonatal rat ventricular myocytes (NRVM) infected with a recombinant adenovirus expressing the human β3-AR (AdVhβ3). We confirmed results in mice with cardiomyocyte-specific moderate expression of human β3-AR (β3-TG) and wild-type (WT) littermates submitted to thoracic transverse aortic constriction (TAC) for 9 weeks. We observed a colocalization of β3-AR with the AMP-activated protein kinase (AMPK) both in neonatal rat and in adult mouse cardiomyocytes. Treatment of NRVM with PE induced hypertrophy and a decrease in phosphorylation of Thr172-AMPK (/2, P = 0.0487) and phosphorylation of Ser79-acetyl-CoA carboxylase (ACC) (/2.6, P = 0.0317), inducing an increase in phosphorylated Ser235/236 S6 protein (×2.5, P = 0.0367) known to be involved in protein synthesis. These effects were reproduced by TAC in WT mice but restored to basal levels in ...Continue Reading
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