Sirtuin 3–dependent mitochondrial dynamic improvements protect against acute kidney injury
Marina Morigi, Luca Perico, Cinzia Rota, Lorena Longaretti, Sara Conti, Daniela Rottoli, Rubina Novelli, Giuseppe Remuzzi, Ariela Benigni
Marina Morigi, Luca Perico, Cinzia Rota, Lorena Longaretti, Sara Conti, Daniela Rottoli, Rubina Novelli, Giuseppe Remuzzi, Ariela Benigni
View: Text | PDF
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

×

Figure 6

SIRT3 counteracts cisplatin-induced mitochondrial dynamic perturbation in injured tubular cells in culture.

Options: View larger image (or click on image) Download as PowerPoint
SIRT3 counteracts cisplatin-induced mitochondrial dynamic perturbation i...
(A) Representative images showing a mitochondrial network of RPTECs untransfected (top) or transfected with SIRT3 plasmid (pSIRT3, bottom) and exposed to medium or cisplatin (5 μM for 24 hours). Insets display fragmented (top) and elongated mitochondria (bottom) visualized by staining with MitoTracker Deep Red. Scale bars: 10 μm. (B and C) Representative Western blots and densitometric analysis of DRP1 and MFF protein expression in mitochondria isolated from control and cisplatin-treated RPTECs overexpressing or not pSIRT3. VDAC protein expression was used as a sample loading control on the same membrane after stripping. *P < 0.05, **P < 0.01, and ***P < 0.001, ANOVA corrected with Bonferroni coefficient. Values are mean ± SEM (n = 3 experiments). (D) Representative images of OPA1 immunofluorescence staining in control and cisplatin-injured RPTECs untransfected (top) or transfected with pSIRT3 (bottom). Nuclei were counterstained with DAPI (blue). Scale bars: 10 μm. (E) Representative Western blot and densitometric analysis of OPA1 protein expression in mitochondria isolated from control or cisplatin-treated RPTECs overexpressing or not pSIRT3. **P < 0.01, and ***P < 0.001, ANOVA corrected with Bonferroni coefficient. Values are mean ± SEM (n = 3 experiments). VDAC blots reported in B, C, and E derive from the same gel.