Molecular interaction between the voltage-dependent anion channel 2 and its agonist efsevin
Final Report Abstract
Cardiovascular diseases (CVDs) continue to dominate mortality trends with a large portion of CVD-related deaths being attributed to cardiac arrhythmia. Still, treatment options for cardiac arrhythmia are limited due to perilous side effects of common antiarrhythmics. Therefore safer new therapies are urgently needed. We have previously demonstrated that the novel synthetic compound efsevin potently suppresses arrhythmogenesis in translational arrhythmia models. This effects was shown to be dependent on the mitochondrial voltage-dependent anion channel 2 (VDAC2). Though efsevin was intensively tested in arrhythmia models the molecular mode of action of the drug remained unknown, making chemical optimization impossible. In this project we therefore evaluated the interaction of efsevin with its target VDAC2 on a biophysical and biochemical level. Using purified VDAC2 we demonstrated that efsevin shifts the open probability of VDAC2 towards a low-conductance state, which is less anion selective. We showed that this effects leads to enhanced uptake of Ca2+ into mitochondria, which in turn explains the anti-arrhythmic effect of efsevin: by enhancing mitochondrial Ca2+ uptake efsevin activates an additional buffering mechanism in cardiomyocytes to blunt erratic spontaneous Ca 2+ release during diastole and thus arrhythmogenesis. In a second line of the project we identified the binding site of efsevin on the VDAC2 protein by computational docking and subsequent mutagenesis. We showed that by binding to a pocket located between the rigid pore-forming β-barrel and a flexible N-terminal α-helix efsevin induces vigorous gating of the channel and a shift towards the less anion selective closed states. Efsevin is bound into this pocket by 2-4 hydrogen bonds and several hydrophobic interactions. Finally, we screened an existing chemical library for additional enhancers of mitochondrial Ca 2+ uptake and identified two FDA and EMA approved drugs with a significantly lower EC 50 compared to efsevin. These substances were further tested in arrhythmia models and we could demonstrate efficacy of both substances to suppress arrhythmogenesis. Taken together we characterized the interaction of the novel antiarrhythmic substance efsevin with its target VDAC2 on a biophysical and biochemical level. Our results shed new light on the physiological and molecular function of VDAC2 in cardiomyocytes. The identification of the binding site allows for computer-aided drug design and further optimization of efsevin. Two newly identified mitochondrial Ca2+ uptake enhancers will further serve for future preclinical and clinical studies on the use of mitochondrial Ca2+ uptake enhancers for the treatment of arrhythmia.
Publications
-
(2020) The antiarrhythmic compound efsevin directly modulates voltage-dependent anion channel 2 by binding to its inner wall and enhancing mitochondrial Ca2+ uptake. British journal of pharmacology 177 (13) 2947–2958
Wilting, Fabiola; Kopp, Robin; Gurnev, Philip A.; Schedel, Anna; Dupper, Nathan J.; Kwon, Ohyun; Nicke, Annette; Gudermann, Thomas; Schredelseker, Johann
-
Disulfiram for the treatment of cardiac diseases, LU100527-B1
Perocchi F, Schredelseker J
-
Ezetimibe for the treatment of cardiac diseases, LU100526-B1
Perocchi F, Schredelseker J
-
(2017) Suppression of Arrhythmia by Enhancing Mitochondrial Ca 2+ Uptake in Catecholaminergic Ventricular Tachycardia Models. JACC Basic Transl Sci, 2(6): 737-747
Schweitzer MK, Wilting F, Sedej S, Dreizehnter L, Dupper NJ, Tian Q, Moretti A, My I, Kwon O, Priori SG, Laugwitz KL, Storch U, Lipp P, Breit A, Mederos y Schnitzler M, Gudermann T, and Schredelseker J
