Sirtuin 3 Activation by Honokiol Decreases Unilateral Ureteral Obstruction-Induced Renal Inflammation and Fibrosis via Regulation of Mitochondrial Dynamics and the Renal NF-κBTGF-β1/Smad Signaling Pathway.

Renal fibrosis is a common feature of all progressive chronic kidney diseases. Sirtuin 3(SIRT3) is one of the mitochondrial sirtuins, and plays a role in the regulation of mitochondrialbiogenesis, oxidative stress, fatty acid metabolism, and aging. Recently, honokiol (HKL), as apharmaceutical SIRT3 activator, has been observed to have a protective effect against pressureoverload-induced cardiac hypertrophy by increasing SIRT3 activity. In this study, we investigatedwhether HKL, as a SIRT3 activator, also has protective effects against unilateral ureteral obstruction(UUO)-induced renal tubulointerstitial fibrosis through SIRT3-dependent regulation ofmitochondrial dynamics and the nuclear factor-κB (NF-κB)/transforming growth factor-β1 (TGF-β1)/Smad signaling pathway. We found that HKL decreased the UUO-induced increase in tubularinjury and extracellular matrix (ECM) deposition in mice. HKL also decreased myofibroblastactivation and proliferation in UUO kidneys and NRK-49F cells. Finally, we showed that HKLtreatment decreased UUO-induced mitochondrial fission and promoted mitochondrial fusionthrough SIRT3-dependent effects. In conclusion, activation of SIRT3 via HKL treatment might havebeneficial effects on UUO-induced renal fibrosis through SIRT3-dependent regulation ofmitochondrial dynamics and the NF-κB/TGF-β1/Smad signaling pathway.