A novel β2-AR agonist, Higenamine, induces β-arrestin-biased signaling.

Abstract

The biased ligands in G protein-coupled receptors (GPCRs) have opened new avenues for developing safer and more effective drugs. However, the identification of such biased ligands as drug candidates is highly desirable. Here, we report that Higenamine, a compound isolated from a Chinese herb, functions as a novel β-arrestin-biased ligand of the β2-adrenergic receptor (β2-AR). The radioligand binding assays demonstrated that Higenamine was the ligand of β2-AR. Higenamine induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), which can be blocked by propranolol, an inhibitor of β2-AR. The Gi protein inhibitor, pertussis toxin, had no effect on the phosphorylation of ERK1/2 induced by Higenamine. Furthermore, Higenamine induced ERK1/2 phosphorylation through transactivation of Epithelial growth factor receptor (EGFR). We also found that Higenamine-induced-ERK1/2 phosphorylation is dependent on β-arrestin1/2, and HG inhibits Doxorubicin-induced cardiomyocyte apoptosis. Our results identify Higenamine as a novel biased ligand via the β-arrestin-dependent pathway. These findings give us a better understanding of Higenamine's potential role in designing diagnostic and therapeutic strategies.