Nobiletin ameliorates hepatic ischemia and reperfusion injury through the activation of SIRT-1/FOXO3a-mediated autophagy and mitochondrial biogenesis

Abstract

Hepatic ischemia and reperfusion injury are characterized by impaired autophagy, mitochondrial dysfunction, and subsequent compromise of cellular homeostasis following hepatic surgery or transplantation. Nobiletin, a natural flavonoid, is a beneficial antioxidant that possesses anti-inflammatory and anti-cancer activities. We investigated the effect of nobiletin on hepatic IR injury and described the underlying mechanisms. C57BL/6 mice were subjected to 60 min of partial hepatic ischemia, treated with nobiletin (5 mg/kg) or vehicle at the start of reperfusion, and killed at 5 h of reperfusion. Hepatic ischemia and reperfusion increased hepatocellular oxidative damage, inflammation, and cell death, but these changes were alleviated upon nobiletin treatment. Nobiletin increased the expression of proteins that control autophagy, mitochondrial dynamics, and biogenesis. Specifically, the SIRT-1/FOXO3a and PGC-1α pathways were activated by nobiletin. IR-induced AKT activation was associated with FOXO3a phosphorylation, which resulted in a significant reduction in the nuclear FOXO3a levels and potentially attenuated autophagy-regulatory gene expression. Nobiletin increased FOXO3a expression and its nuclear translocation via the inhibition of AKT. Specific inhibition of SIRT-1 abolished the protective effect of nobiletin, causing decreased FOXO3a expression, followed by autophagy induction and decreased PGC-1α expression and mitochondrial dynamics. Taken together, our data indicate that SIRT-1 directly mediates the protective effect of nobiletin against hepatic ischemia and reperfusion injury. The activation of autophagy and mitochondrial function through the SIRT-1/FOXO3a and PGC-1α pathways indicate that nobiletin could have therapeutic potential for treating hepatic ischemia and reperfusion injury.

P2Y2R contributes to the development of diabetic nephropathy by inhibiting autophagy response

“…To determine the potential mechanism of P2Y2R in regulation of autophagy in DN mice, the expression of p-AKT, p-FOXO3a, p-ULK1, p-Beclin-1 and SIRT-1 were evaluated by western blot analysis. FOXO3a plays a critical role in regulating autophagy in various diseases; in response to stress or pathological conditions, FOXO3a is phosphorylated by AKT and is retained in the cytosol, thereby blocking its transcriptional activity [ 1 , [37] , [38] , [39] ]. Consistently, we found that the levels of phosphorylation in AKT (Ser473) and its substrate FOXO3a (Ser253) were significantly increased in WT DN mice compared to WT control mice, while the levels were decreased in KO DN mice ( Figure 6 A).…”

“…Furthermore, SIRT-1 has been assigned to a renoprotective effect by modulating autophagy response through deacetylation of multiple transcription factors including FOXO3a in DN [ 11 , 37 ]. Because SIRT-1 and FOXO3a signalling play a key role in autophagy induction [ 1 , 38 , 40 ], we examined the effect of P2Y2R deficiency on SIRT-1 and FOXO3a expression in DN. The protein and mRNA levels of SIRT-1 and FOXO3a were significantly downregulated in WT DN mice, while the levels were restored in KO DN mice ( Figure 6 A, B).…”

“…In response to stress or pathologic conditions, FOXO3a is phosphorylated by AKT and retained in the cytosol, resulting in the suppression of transcriptional activity [ 1 , [37] , [38] , [39] ]. Consistently, our study showed that activation of AKT increased the FOXO3a phosphorylation and suppressed FOXO3a-mediated transcriptional activity required for autophagy induction, facilitating the pathogenesis of DN.…”

Flavonoids from Aurantii Fructus Immaturus and Aurantii Fructus: promising phytomedicines for the treatment of liver diseases

“…1. Numerous studies have reported that HD, NIN and NOB are the most potent hepatoprotective ingredients against liver injury induced by clinical ischemia-reperfusion (IR), paraquat (PQ), carrageenan, cyclophosphamide (CYP), carbon tetrachloride (CCl 4 ) and other stimulants [27][28][29][30]. Recently, several studies have revealed that NRG, TN, HT and ED also contribute to the pharmacological effects of AFI in the treatment of liver diseases.…”

“…Furthermore, Wu et al explored the protective effects of NOB against IR injury after liver transplantation and found that NOB (50 mg/kg) inhibited the activation of TLR4/NF-κB signaling pathway and the downstream expression of inflammatory mediators in activated Kupffer cells, which then decreased the hepatic infiltration of macrophages and CD4 + lymphocytes, and suppressed liver inflammation [ 27 ]. Recently, it has also been reported that NOB (5 mg/kg) downregulates autophagy-regulatory gene expression, increases forkhead box O3 a (FOXO3a) expression and its nuclear translocation by activating SIRT-1, AKT and PPARγ coactivator-1α (PGC-1α) pathways, which in turn attenuates hepatocyte apoptosis and inflammation in mice with IR injury [ 29 ]. These findings suggest that NOB may possess therapeutic potential for treating liver IR injury or have protective property for liver preservation during transplantation.…”