Abstract
Perturbation of proximal tubule (PT) lipid metabolism fuels the pathological features of acute kidney injury (AKI). We found that AKI induced biosynthesis of lipotoxic ceramides within PTs in humans and mice and that urine ceramides predicted disease severity in children and adults. Mechanistic studies in primary PTs, which included a thermal proteomic profiling screen for ceramide effectors, revealed that ceramides altered assembly of the mitochondrial contact site and cristae-organizing system (MICOS) and respiratory supercomplexes, leading to acute disruption of cristae architecture, mitochondrial morphology, and respiration. These ceramide actions were dependent on the presence of the 4,5-trans double bond inserted by dihydroceramide desaturase 1 (DES1). Genetically ablating DES1 preserved mitochondrial integrity and prevented kidney injury in mice following bilateral ischemia reperfusion. Moreover, novel DES1 inhibitors that are attractive clinical drug candidates phenocopied the DES1 knockouts. These studies describe a new, therapeutically tractable mechanism underlying PT mitochondrial damage in AKI.
Keywords:
ETC; MICOS; acute kidney injury; ceramides; cristae; lipid metabolism; lipidomics; metabolism; mitochondria; proximal tubule; sphingolipids.