BACKGROUND: Glycogen synthase kinase (GSK)-3β/β-catenin signaling regulates ischemia-reperfusion (I/R)-induced apoptosis and proliferation, and inhibition of GSK-3β has beneficial effects on I/R injury in the heart and the central nervous system. However, the role of this signaling in hepatic I/R injury remains unclear. The present study aimed to investigate the effects and mechanism of GSK-3β/β-catenin signaling in hepatic I/R injury.
METHODS: Male C57BL/6 mice (weighing 22-25 g) were pretreated with either SB216763, an inhibitor of GSK-3β, or vehicle. These mice were subjected to partial hepatic I/R. Blood was collected for test of alanine aminotransferase (ALT), and liver specimen for assays of phosphorylation at the Ser9 residue of GSK-3β, GSK-3β activity, axin 2 and the anti-apoptotic factors Bcl-2 and survivin, as well as the proliferative factors cyclin D1 and proliferating cell nuclear antigen, and apoptotic index (TUNEL). Real-time PCR, Western blotting and immunohistochemical staining were used.
RESULTS: SB216763 increased phospho-GSK-3β levels and suppressed GSK-3β activity (1880±229 vs 3280±272 cpm, P<0.01). ALT peaked at 6 hours after reperfusion. Compared with control, SB216763 decreased ALT after 6 hours of reperfusion (4451±424 vs 7868±845 IU/L, P<0.01), and alleviated hepatocyte necrosis and vacuolization. GSK-3β inhibition led to the accumulation of β-catenin in the cytosol (0.40±0.05 vs 1.31±0.11, P<0.05) and nucleus (0.62±0.14 vs 1.73±0.12, P<0.05), β-catenin further upregulated the expression of axin 2. Upregulation of GSK-3β/β-catenin signaling increased Bcl-2, survivin and cyclin D1. Serological and histological analyses showed that SB216763 alleviated hepatic I/R-induced injury by reducing apoptosis (1.4±0.2% vs 3.6±0.4%, P<0.05) and enhanced liver proliferation (56±8% vs 19±4%, P<0.05).
CONCLUSION: Inhibition of GSK-3β ameliorates hepatic I/R injury through the GSK-3β/β-catenin signaling pathway.