Protection against acute kidney injury

Acute kidney injury (AKI) affects millions of patients worldwide, with a mortality rate exceeding 50%. While it is known that mitochondrial dysfunction contributes to tubular injury, treatments to hasten renal repair have been hindered by the lack of plausible pharmacologic targets. Marina Morigi and colleagues at the Mario Negri Institute for Pharmacological Research have uncovered a renoprotective role for the NAD-dependent deacetylase sirtuin 3 (SIRT3) and shown that pharmacologic activation of SIRT3 counteracts cisplatin-induced renal failure. In a cisplatin-induced murine model of AKI, treatment of WT mice with SIRT3-boosting drugs, including the AMPK agonist AICAR and the antioxidant acetyl-L-carnitine (ALCAR), decreased tubular injury and improved renal function. In contrast, administration of AICAR and ALCAR to SIRT3-null mice following cisplatin-induced injury did not improve survival. The authors determined that in addition to restoring SIRT3 activity, AICAR and ALCAR treatment decreased cisplatin-induced mitochondrial fragmentation. In vitro, SIRT3 preserved mitochondrial membrane integrity in cisplatin-treated human tubular cells by preventing aberrant membrane depolarization and mitophagy. Together, the results of this study provide insight into the role of SIRT3 in protection against AKI and suggest AICAR and ALCAR as potential therapeutic agents for limiting AKI-associated damage. The accompanying image shows representative transmission electron micrographs of the proximal renal tubules of WT (left) and cisplatin-treated mice (right), illustrating the decreased mitochondrial density and fragmentation in response to kidney injury. 

Published January 20, 2015, by Melissa Hector-Greene

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Sirtuin 3–dependent mitochondrial dynamic improvements protect against acute kidney injury
Marina Morigi, … , Giuseppe Remuzzi, Ariela Benigni
Marina Morigi, … , Giuseppe Remuzzi, Ariela Benigni
Published January 20, 2015
Citation Information: J Clin Invest. 2015;125(2):715-726. https://doi.org/10.1172/JCI77632.
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Research Article Nephrology

Sirtuin 3–dependent mitochondrial dynamic improvements protect against acute kidney injury

Abstract

Acute kidney injury (AKI) is a public health concern with an annual mortality rate that exceeds those of breast and prostate cancer, heart failure, and diabetes combined. Oxidative stress and mitochondrial damage are drivers of AKI-associated pathology; however, the pathways that mediate these events are poorly defined. Here, using a murine cisplatin-induced AKI model, we determined that both oxidative stress and mitochondrial damage are associated with reduced levels of renal sirtuin 3 (SIRT3). Treatment with the AMPK agonist AICAR or the antioxidant agent acetyl-l-carnitine (ALCAR) restored SIRT3 expression and activity, improved renal function, and decreased tubular injury in WT animals, but had no effect in Sirt3–/– mice. Moreover, Sirt3-deficient mice given cisplatin experienced more severe AKI than WT animals and died, and neither AICAR nor ALCAR treatment prevented death in Sirt3–/– AKI mice. In cultured human tubular cells, cisplatin reduced SIRT3, resulting in mitochondrial fragmentation, while restoration of SIRT3 with AICAR and ALCAR improved cisplatin-induced mitochondrial dysfunction. Together, our results indicate that SIRT3 is protective against AKI and suggest that enhancing SIRT3 to improve mitochondrial dynamics has potential as a strategy for improving outcomes of renal injury.

Authors

Marina Morigi, Luca Perico, Cinzia Rota, Lorena Longaretti, Sara Conti, Daniela Rottoli, Rubina Novelli, Giuseppe Remuzzi, Ariela Benigni

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