Phosphorylation status of heat shock protein 27 regulates the interleukin-1β-induced interleukin-6 synthesis in C6 glioma cells.

Heat shock protein 27 (HSP27), a low-molecular-weight HSP, is recognized as a molecular chaperone. In response to various stimuli, HSP27 expression is induced in the CNS. However, the exact roles of HSP27 in the CNS have not yet been clarified. It has been reported that interleukin (IL)-1β stimulates IL-6 synthesis in C6 glioma cells. In the present study, we investigated the role of HSP27 in the IL-1β-induced IL-6 synthesis in C6 cells. IL-1β alone did not affect the levels of HSP27. The IL-1β-induced IL-6 release in HSP27-downregulated C6 cells were enhanced compared with those in control siRNA-transfected cells. On the other hand, the IL-1β-induced IL-6 release was significantly enhanced in C6 cells transfected with HSP27 than those in control cells in time- and dose-dependent manner. The IL-1β-induced IL-6 release and the mRNA expression were markedly suppressed in C6 cells transfected with phosphorylated HSP27, while those in the cells transfected with unphosphorylated HSP27 were enhanced. In conclusion, these results strongly suggest that phosphorylated status of HSP27 has a switching role in the IL-1β-induced IL-6 synthesis in C6 glioma cells.