Objective:To evaluate the role of hippocampal prostaglandin-endoperoxide synthase 2 (PTGS2) in baicalin-induced reduction of cognitive dysfunction after cerebral ischemia-reperfusion injury (CIRI) in mice.Methods:Thirty healthy male C57BL/6 mice, aged 16 weeks, weighing 20-25 g, were divided into 5 groups ( n=6 each) using a random number table method: control group (C group), CIRI group, baicalin+ CIRI group (B+ CIRI group), overexpression of PTGS2+ CIRI group (PTGS2+ CIRI group), and overexpression of PTGS2+ baicalin+ CIRI group (PTGS2+ B+ CIRI). In B+ CIRI group and PTGS2+ B+ CIRI group, baicalin-liposome 0.2 ml was injected through the tail vein, and the CIRI model was established 1 week later. In PTGS2+ CIRI group and PTGS2+ B+ CIRI group, PTGS2-overexpressed adeno-associated virus 1.2 μl was injected into the hippocampus, and the CIRI model was established 4 weeks later. CIRI model was established by using the transient (50 min) bilateral common carotid artery occlusion/reperfusion. On the 12th day after developing the model, the spatial learning and memory ability was evaluated using Morris water maze test. The expression of PTGS2 in the hippocampus was detected by Western blot, and the expression of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), IL-6, Iba-1 and CD68 mRNA in the hippocampus was detected by quantitative real-time polymerase chain reaction. Results:Compared with C group, the escape latency was significantly prolonged, the time spent in the target quadrant was shortened, the number of crossing the original platform was reduced, and the expression of PTGS2 and expression of Iba-1, CD68, TNF-α, IL-1β and IL-6 mRNA in the hippocampus was up-regulated in CIRI group ( P<0.05). Compared with CIRI group, the escape latency was significantly shortened, the time spent in the target quadrant was prolonged, the number of crossing the original platform was increased, and the expression of PTGS2 and expression of Iba-1, CD68, TNF-α, IL-1β and IL-6 mRNA in the hippocampus was down-regulated in B+ CIRI group, and the escape latency was significantly prolonged, the time spent in the target quadrant was shortened, the number of crossing the original platform was reduced, and the expression of PTGS2 and expression of Iba-1, CD68, TNF-α, IL-1β and IL-6 mRNA in the hippocampus was up-regulated in PTGS2+ CIRI group ( P<0.05). Compared with B+ CIRI group, the escape latency was significantly prolonged, the time spent in the target quadrant was shortened, the number of crossing the original platform was reduced, and the expression of PTGS2 and expression of Iba-1, CD68, TNF-α, IL-1β and IL-6 mRNA in the hippocampus was up-regulated in PTGS2+ B+ CIRI group ( P<0.05). Conclusions:The mechanism by which baicalin attenuates cognitive dysfunction after CIRI is related to down-regulation of hippocampal PTGS2 expression and inhibition of neuroinflammation in mice.

Objective:To investigate the role of protein phosphatase 4 catalytic subunit (PP4C) in regulating hepatitis B virus X protein (HBx) levels and its effects on the biological functions of HBx, thus to provide a potential therapeutic targets for hepatitis B virus (HBV)-related hepatocellular carcinoma.Methods:In vivo and in vitro interactions between HBx and PP4C were analyzed by co-immunoprecipitation (Co-IP) and GST pull-down assay. Recombinant plasmids of PP4C and HBx were co-transfected with Lipofectamine 3000 reagents into hepatoma cells to detect the protein levels of HBx by Western blot. The half-life of HBx in the transfected cells treated with cycloheximide (CHX) were detected. The phosphorylation assay was used to evaluate the effects of PP4C on HBx phosphorylation. CCK8 assay, wound healing assay and Matrigel invasion chamber assay were used to analyze the effects of PP4C on the biological functions of HBx. Results:PP4C interacted with HBx in vivo and in vitro. PP4C overexpression significantly increased the protein level and stability of HBx and the phosphorylation assay confirmed that PP4C overexpression decreased the serine phosphorylation of HBx in hepatoma cells. PP4C overexpression enhanced the migration and invasion of hepatoma cells, but had no significant effects on the proliferation. Conclusions:The interactions between HBx and PP4C promoted the stability of HBx and ultimately enhanced the migration and invasion of hepatoma cells, and the mechanisms might be related to the decrease of HBx serine phosphorylation by PP4C. This study provided a theoretical basis for further investigation of the pathogenic mechanisms of HBx, and targeting PP4C and HBx interaction might provide insights for developing novel treatment for HBV-related hepatocellular carcinoma.