Narrow Results

Curcumin is a hydrophobic polyphenol derived from turmeric: the rhizome of the herb Curcumalonga. Autophagy is an evolutionarily conserved process, in which cellular proteins and organelles are engulfed in autophagosome and then fuses with lysosome for degradation. Our previous study showed that Curcumin activates lysosome and induce autophagy through inhibition of AKT (protein kinase K, PKB)-mammalian target of rapamycin (mTOR) pathway. But whether Curucmin affects the fusion of autophagosome-lysosome is still not clear. Here, we used Curcumin-probe conjugation with an alkyne moiety to label mouse embryonic fibroblasts (MEFs) and found that Curcumin targets autophagy-related proteins, enhances autophagic flux and activates lysosome in cells. Moreover, Curcumin treatment promotes the fusion of autophasosome-lysosome in MEFs. Second, the enhanced fusion of autophagosome-lysosome is attributed to mTOR suppression. Third, blockage of the autophagosome-lysosome fusion leads to cell growth inhibition by Curcumin. Taken together, data from our study indicates the importance of the fusion of autophagosome-lysosome in Curcumin-induced autophagy, which may facilitate the development of Curcumin as a potential therapeutic agent for oxidative stress-related diseases.

Graphene oxide (GO) is a promising nanomaterial for application in a variety of biomedical fields, including neuro-oncology, neuroimaging, neuroregeneration and drug delivery. Microglia are the central macrophage-like cells critically involved in neuroimmunity. However, the interaction between GO and microglia remained mostly unknown. The present study investigated the influence of GO on the production of proinflammatory cytokines by microglia. Primary murine microglial cells were treated with GO (1–25 μg/mL) followed by stimulation with lipopolysaccharide (LPS) for 24 h. The cell viability was measured by spectrophotometry using AlamarBlueⓇ. The levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA). The IL-1β converting enzyme (ICE) activity was measured using a specific fluorescent substrate. The activity of cathepsin B and the lysosomal permeability and alkalinity were determined by flow cytometry. Treatment with GO did not affect cell viability, but significantly suppressed the production of IL-1β. In contrast, the production of TNF-α was unaltered. In addition, the lysosomal permeability and alkalinity in microglia treated with GO were increased, whereas the activity of cathepsin B and ICE was decreased. Collectively, these results demonstrated that exposure to GO differentially affected the production of proinflammatory cytokines, which is associated with the modulation of the lysosomal pathway of cytokines processing.