Small Interfering RNA Targeting Mitochondrial Calcium Uniporter Improves Cardiomyocyte Cell Viability in Hypoxia/Reoxygenation Injury by Reducing Calcium Overload

Abstract

Intracellular Ca2+ mishandling is an underlying mechanism in hypoxia/reoxygenation (H/R) injury that results in mitochondrial dysfunction and cardiomyocytes death. These events are mediated by mitochondrial Ca2+ (mCa2+) overload that is facilitated by the mitochondrial calcium uniporter (MCU) channel. Along this line, we evaluated the effect of siRNA-targeting MCU in cardiomyocytes subjected to H/R injury. First, cardiomyocytes treated with siRNA demonstrated a reduction of MCU expression by 67%, which resulted in significant decrease in mitochondrial Ca2+ transport. siRNA treated cardiomyocytes showed decreased mitochondrial permeability pore opening and oxidative stress trigger by Ca2+ overload. Furthermore, after H/R injury MCU silencing decreased necrosis and apoptosis levels by 30% and 50%, respectively, and resulted in reduction in caspases 3/7, 9, and 8 activity. Our findings are consistent with previous conclusions that demonstrate that MCU activity is partly responsible for cellular injury induced by H/R and support the concept of utilizing siRNA-targeting MCU as a potential therapeutic strategy.

MCU Up‐regulation contributes to myocardial ischemia‐reperfusion Injury through calpain/OPA‐1–mediated mitochondrial fusion/mitophagy Inhibition

“…and participates in I/R injury through the mechanism of MCU-Ca 2+ overload-mPTP opening. 8,19,20 In the present study, mito- 9 Previous studies have shown that calpain activation can cause cardiac dysfunction and apoptosis through a variety of signalling pathways. 23 In mitochondria, activated calpain cleaves and modifies apoptosis-inducing factor in mitochondria to release it from mitochondria to cytoplasm and initiate apoptosis.…”

Amorphous SiO2 nanoparticles promote cardiac dysfunction via the opening of the mitochondrial permeability transition pore in rat heart and human cardiomyocytes

“…Finally, it is of our concern the occupational exposure to NPs, especially those individuals with a cardiovascular disease. Recent work has shown that NP exposure exacerbates the cardiovascular damage, such as nanoSiO 2 induced alterations associated to contractile dysfunction [15,18] or pathophysiological conditions in which there is an increase of oxidative stress, such as myocardial ischemia or angina [39,48]. In this context, the tissue of patients will have higher susceptibility, which could trigger not only a lower dose cytotoxicity, but will likely provoke a nonconventional toxicity mechanism in specific scenarios of the disease, for example a patient with heart failure or cardiac hypertrophy [21].…”

Ex Vivo Cardiotoxicity of Antineoplastic Casiopeinas Is Mediated through Energetic Dysfunction and Triggered Mitochondrial-Dependent Apoptosis

“…The mitochondrial membrane potential was measured by fluorometry using 5 μ M safranine [ 13 ]. Mitochondrial Ca 2+ uptake was determined with the metalochromic indicator, Arsenazo III, or calcium green 5N (5N-CG) [ 18 , 19 ], using a medium containing 50 μ M Arsenazo or 10 μ M 5N-CG, 10 mM succinate plus rotenone (0.1 μ g·ml −1 ), 200 μ M ADP, and 0.25 μ g oligomycin A. Pulses of 10 nmol Ca +2 were added every 3 minutes to reach a Ca +2 release due to MPT opening. Mitochondrial cytochrome c quantification from Cas-treated hearts was performed using Western blot analysis as described previously [ 11 ].…”