FNDC5 and acute kidney injury: Renal tubular cells have the most abundant mitochondrial content.21 Damaged or malfunctioning mitochondria are cleared by mitochondrial autophagy.19,22,23 Mitochondrial autophagy limits and repairs organ damage by ischemia and hypoxia.24 Thus, we hypothesize that irisin may preserve the mitochondrial integrity and function in renal tubular epithelial cells and protect against I/R-induced AKI.