Elevation of Ser9 phosphorylation of GSK3ß is required for HERV-W env-mediated BDNF signaling in human U251 cells.

Human endogenous retrovirus W family (HERV-W) envelope (env) is known to be associated with neurological and psychiatric disorders, such as multiple sclerosis and schizophrenia. Previous studies showed that overexpression of HERV-W env could induce brain-derived neurotrophic factor (BDNF) gene expression. In human and rat cells, BDNF-mediated signal transduction might be modulated by glycogen synthase kinase 3ß (GSK3ß). Both BDNF and GSK3ß are schizophrenia-related genes. In this paper, we investigated whether GSK3ß was involved in the HERV-W env-induced expression of BDNF. We found that HERV-W env increased phosphorylation of GSK3ß at Ser9 (p-GSK3ß (Ser9)) and the ratio of p-GSK3ß (Ser9) to total GSK3ß (p<0.05) in U251 cells. Overexpression of HERV-W env led to a 36.2% reduction in GSK3ß activity compared to control (p<0.05). The levels of ß-catenin, cyclin D1 and TSC2 mRNAs were upregulated (p<0.05). These data suggested that overexpression of HERV-W env might activate the GSK3ß signaling pathway in U251 cells. Further, knockdown of GSK3ß reduced the expression of total GSK3ß, p-GSK3ß (Ser9), and the ratio of p-GSK3ß (Ser9) to total GSK3ß by 28.6%, 50.4%, and 30.2%, respectively (p<0.05). Levels of ß-catenin, cyclin D1 and TSC2 mRNAs were also reduced (p<0.05). Interestingly, GSK3ß activity increased (p<0.05). Knockdown of GSK3ß also decreased mRNA and protein expression of BDNF by 49.9% and 48.5% respectively (p<0.05). These results indicated that phosphorylation of GSK3ß at Ser9 might be involved in HERV-W env-induced BDNF expression, and will hopefully improve our understanding of the role of HERV-W env in neurological and psychiatric diseases (schizophrenia, etc).

In vitro antioxidant and antiproliferative effects of ellagic acid and its colonic metabolite, urolithins, on human bladder cancer T24 cells.

Urolithins were the metabolites of ellagic acid by intestinal flora in gastrointestinal tract. In previous research, it was found that urolithins could mainly inhibit prostate cancer and colon cancer cell growth. However, there is no report about bladder cancer therapy of urolithins. In this paper, three urolithin-type compounds (urolithin A, urolithin B, 8-OMe-urolithin A) and ellagic acid were evaluated for antiproliferative activity in vitro against human bladder cancer cell lines T24. The IC50 values for T24 cell inhibition were 43.9, 35.2, 46.3 and 33.7 µM for urolithin A, urolithin B, 8-OMe-urolithin A and ellagic acid, respectively. After the administration of urolithins and ellagic acid, we found these compounds could increase mRNA and protein expression of Phospho-p38 MAPK, and decrease mRNA and protein expression of MEKK1 and Phospho-c-Jun in T24 cells. Caspase-3 was also activated and PPAR-γ protein expression increased in drug-induced apoptosis. And what's more, the antioxidant assay afforded by three urolithins and EA treatments were associated with decreases in the intracellular ROS and MDA levels, and increased SOD activity in H2O2-treated T24 cells. The results suggested that these compounds could inhibit cell proliferation by p38-MAPK and/or c-Jun medicated caspase-3 activation and reduce the oxidative stress status in bladder cancer.