Exosomes secreted from endothelial cells affected the electrophysiological properties of cardiomyocytes via miR-126-3p in Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TTC) is characterized by an acute, transient and reversible left ventricular (LV) systolic dysfunction with endothelial dysfunction being one of its pathophysiological mechanisms. Endothelial dysfunction manifests as an imbalance between factors regulating vasoconstriction and vasodilation. However, the precise molecular mechanism underlying the interaction between endothelial cells and cardiomyocytes remains unclear. Here, we demonstrate that the expression of miR-126-3p in serum-exosomes was significantly upregulated in TTC patients, compared to healthy patients and recovered TTC patients. High concentration of epinephrine (Epi) suppressed the depolarization velocity (Vmax), prolonged duration of action potentials (APD) and induced arrhythmic events in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Exosomes (Exo) derived from human coronary microvascular endothelial cells (HCMECs) without Epi-treatment (Wt-exo) reversed the effects of Epi on action potentials and ion channel gene expression and currents in hiPSC-CMs. Exosomes derived from Epi-treated HCMECs (Epi-exo) mimicked or exacerbated the effects of Epi. Epi increased the levels of miR-126-3p in both HCMECs and their exosomes, indicating a potential role of miR-126-3p in mediating the effects of Epi-exo in hiPSC-CMs. Exo overexpressing miR-126-3p mimicked the effects of Epi-exo, confirming the significant involvement of miR-126-3p in Epi-exo effects. Dual luciferase reporter assay coupled with gene mutation techniques identified a targeting site of miRNA-126-3p in G‑protein signaling 3 (RGS3) gene. Western blot and qPCR analyses displayed that miR-126-3p mimic reduced RGS3 expression level in both HCMECs and hiPSC-CMs, confirming the inhibitory effects of miR-126-3p on RGS3 signaling. Taken together, our findings uncovered for the first time that the exosomal miR-126-3p derived from endothelial cells can induce ion channel dysfunction by targeting RGS3 signaling in cardiomyocytes. This study may potentially offer new insights into pathogenesis of TTC.