烟碱抑制RAW264.7细胞表达和释放HMGB1的机制

目的:探讨烟碱抑制RAW264.7细胞HMGB1表达和释放的机制。方法:(1)RAW264.7细胞在6孔板分组培养:仅加培养液为对照组(C);加LPS250μg/L为LPS组(LPS);在LPS基础上加烟碱1μmol/L和10μmol/L分别为烟碱1组(N1)和烟碱2组(N2)。培养24h后,RT-PCR检测各组细胞HMGB1 mRNA表达水平;Western blotting检测上清液和胞浆、胞核HMGB1含量。(2)用鼠α7nAChR基因反义和正义链RNA转染培养细胞后,再加含LPS250μg/L和10μmol/L烟碱于培养液分别作为反义链组(antisense RNA)和正义链组(senseRNA);以上述C组和LPS组为对照,2h后Western blotting检测上清液HMGB1量。结果:(1)C组细胞HMGB1 mRNA呈低水平表达(1659.20±121.05);细胞HMGB1 mRNA表达水平在N1和N2组及LPS组间差异无显著(P0.05)。(2)LPS组上清液的HMGB1量较高(445.34±28.52);N1和N2组上清液的HMGB1量显著低于LPS组(P0.05)。(3)C组胞核HMGB1量较高(335.46±12.24);而LPS组胞核HMGB1量明显低于对照组(P0.05);N1组和N2组胞核HMGB1显著高于LPS组(P0.05)。(4)AntisenseRNA组与LPS组比,培养液中HMGB1量无显著差异(P0.05);senseRNA组与LPS组比,HMGB1含量明显减少(P0.05)。结论:烟碱对RAW264.7细胞释放HMGB1有明显抑制作用;其主要机制可能是通过与α7nAChR特异结合而影响HMGB1的核转位。

Inhibition of HMGB1 expression and release by nicotine in RAW264.7 cells

AIM: To investigate that nicotine inhibits HMGB1 expression and release in RAW264.7 cells.METHODS: (1) RAW264.7 cells were cultured in 6 wells plate, treated with 250 μg/L LPS and 1 μmol/L or 10 μmol/L nicotine, in which the cells treated with or without 250 μg/L LPS were regarded as nicotine 1 group (N1), nicotine 2 group (N2), LPS group (LPS) and control group (C), respectively. HMGB1 protein in the cell culture media and in cell nuclear was examined by Western blotting and the cellular HMGB1 mRNA level was detected by RT-PCR. (2) Transfected with antisense RNA or sense RNA of α~7 subunit-containing nicotinic receptor (α~7nAChR), RAW264.7 cells were treated with 250 μg/L LPS and 10 μmol/L nicotine, HMGB1 protein in the culture media was also tested by Western blotting.RESULTS: (1) HMGB1 mRNA level in C group was low (1 659.20±121.05) and no significant statistical difference among groups of N1, N2 and LPS was observed (P>0.05). (2) Higher HMGB1 accumulation in the cell culture media was detected in LPS group (445.34±28.52) than that in C group. Compared to LPS group, both N1 and N2 groups distinctly attenuated HMGB1 accumulation in culture media (P<0.05). (3) Nuclear HMGB1 accumulation was lower in LPS group than that in C group, and two different nicotine concentrations markedly increased the nuclear HMGB1 accumulation compared to LPS group (P<0.05). (4) No significant difference of HMGB1 levels in culture media between antisense RNA group and LPS group was observed (P>0.05). In sense RNA group, however, HMGB1 level was observably reduced compared to antisense group (P<0.05).CONCLUSION: The present results suggest that nicotine dramatically inhibits RAW264.7 cell nuclear HMGB1 translocation and extracellular release, and this effect relies on α~7nAch receptor expression.