FNDC5 and myocardial infarction: This hypothesis is supported by both in vivo and in vitro experiments that showed that GTPase OPA1, which is responsible for the regulation of mitochondrial dynamics and is crucial for adapting mitochondrial function and preserving cellular health, is downregulated in the infarcted heart, whereas irisin treatment upregulated its expression and protected cardiomyocytes from further damage after myocardial infarction [135].