Maurocalcine effects on calcium homeostasis in adult rat cardiomyocytes and human iPS cells derived cardiomyocytes

Abstract

Ryanodine receptors type 2 (RyR2) the intracellular channels that control excitation-contraction (EC) coupling in cardiomyocytes represent an important target for treatment of arrhythmias accompanying cardiac pathologies. Maurocalcine (MCa), a peptide isolated from scorpion venom, has been described as a high affinity activator of RyR in skeletal muscle. Phosphorylation of MCa has been shown to induce a complete remodelling of its effect on RyR, making it a negative allosteric modulator of RyR. The purpose of this study is to characterize the effects of MCa and different analogues on EC coupling in isolated adult ventricular cardiomyocytes and hiPS-derived cardiomyocytes (hiPS-CMs). Adult ventricular myocytes were isolated from 3–6 months-old Sprague Dawley rats with conventional collagenase type II and protease type XIV mix, and hiPS-CMs were obtained from urine cells of healthy volunteers. Changes of cytoplasmic calcium concentration were measured using Fura-2 and IonOptix software. hiPS-CMs contractions and extrafield potentials were recorded with CardioExcyte system (Nanion). We first confirmed binding between MCa and RyR2. Next, we showed that MCa (500nM) induces asynchronous calcium release and contractions of isolated adult rat cardiomyocytes under electrical stimulation at 1Hz. Similar results were observed on hiPS-CMs in the presence of MCa. Effects of native MCa and analogues on isoprenaline-mediated stimulation of RyR2 are under investigation. Our results demonstrate that MCa penetrates adult cardiomyocytes as well as human iPS derived cardiomyocytes and modulates RyR2 activity. MCa analogues exhibit different effects on RyR2, from positive to negative allosteric modulation. These results provide promising evidence that MCa could be used as an in cellulo modulator of RyR2 to control abnormal RyR activity in pathological situations.