The Study On LPS Inducing HIF-1α Expression In RAW264.7 Cells Under Hypoxia By Simultaneously Activating P38/MAPK And NF-κB Signal Pathways

Objective:To investigate the effect of hypoxia-induced factor-1α(HIF-1α) expression in LPS-induced RAW264.7 cells under hypoxia condition.Methods:RAW264.7 cells were cultured with demanded concentration of LPS(ug/ml) for 1,3,6,9,12 h under hypoxia condition.The expression of HIF-1α protein level was detected by Western blotting and m RNA level by Q-PCR.Meanwhile, signal molecules related with p38/MAPK and NF-κB signaling pathways were measured. The change of HIF-1α expression was observed after cells treated with specific inhibitors of p38/MAPK and NF-κB. The change of inflammatory cytokines such as TNFα, PGE2, IL-1β secreted by LPS-induced raw264.7cells and the expression of osteoclast-specific markers such as Traf6,Nfatc1,Ctsk,c Fos,Trap were measured by ELISA and Fluorescence quantitative PCR after knockdown on HIF-1α expression by small inteferring RNA.Results:(1)Under hypoxia,HIF-1α expression was significantly increased by LPS(p<0.05).(2)LPS up-regulated of the phosphorylation of p38/MAPK and activated NF-κB,but the expression of HIF-1α was suppressed by specific inhibitors of p38/MAPK and NF-κB under hypoxia signifcantly(p<0.05)。(3)After application of si RNA targeting HIF-1a,LPS caused significant suppression on the level of PGE2, IL-1β and the expression of osteoclast-specific markers in RAW264.7 cells under hypoxia condition(p<0.05).Conclusion:(1)LPS induced HIF-1α expression of RAW264.7 cells under hypoxia possibly by simultaneously activating the p38/MAPK and NF-κB signal pathway.(2)The application of si RNA targeting HIF-1a could effectively suppress the expression of inflammatory cytokines and osteoclast-differentiation of LPS-induced RAW264.7 cells under hypoxia condition.