Phencynonate mediates antidepressant response by activating sirtuin 6-SOD2/Prdx6 pathway

Highlights: • PHH activates SIRT6 expression by increasing NAD⁺/NADH ratio. • SIRT6 directly deacetylates SOD2 and Prdx6 at Lys68/122 and Lys63/209. • PHH modulates antioxidant capacity by up-regulating SIRT6 deacetylation activity. • PHH may be developed as a therapeutic drug for the treatment of MDD patients. Major depression is a highly prevalent disorder with no effective medical treatments available. Recent evidence has shown that sirtuins (SIRTs) signaling has been implicated to play an essential in the pathogenesis of depression. Here in this study, we aimed to investigate the potential role of the phencynonate hydrochloride (PHH) in rat models of chronic unpredictable mild stress (CUMS)-induced depression. SIRT6 expression was up-regulated by PHH via increasing NAD⁺/NADH ratio in the prefrontal cortex. PHH was able to suppress CUMS-induced oxidative stress and enhance the antioxidant capacity and antioxidant proteins activity, such as superoxide dismutase 2 (SOD2) and peroxiredoxin 6 (Prdx6). In vitro study, we found that SIRT6 directly bound to SOD2 and Prdx6 and deacetylated them at Lys68/122 and Lys63/209, which were acetylated by p300/CBP-associated factor (PCAF). Finally, we showed that PHH ameliorated CUMS-induced depressive phenotypes by up-regulating SIRT6 deacetylation activity. In summary, PHH-mediating SIRT6 pathway is required for antidepressant response and PHH can be used as a novel therapeutic to effectively treat depression.