镧抑制内毒素/脂多糖激活NF-κB信号通路的分子机制探讨

The molecular mechanisms underlying the inhibiting effects of lanthanum on lipopolysaccharide induced NF-κB activation

目的 分析镧调控内毒素/脂多糖（LPS）激活巨噬细胞核因子-κB（NF-κB）信号通路的分子机制.方法 体外培养RAW264.7小鼠巨噬细胞,随机分为：LaCl3 ＋LPS组、LPS对照组、LaCl3对照组和空白对照组.免疫细胞化学法分析p65蛋白核转位情况；分别提取细胞总蛋白或胞核胞质蛋白,ELISA法测胞核蛋白中p65蛋白与靶基因结合的活性；Western blot分析胞核蛋白中p65蛋白、胞质中核因子抑制蛋白α（IκBα）和磷酸化的核因子抑制蛋白α（p-IκBα）水平,及总蛋白IKK激酶的表达和磷酸化情况.结果 镧可阻断LPS诱导p65蛋白活化,如抑制其核转位、降低其在胞核中的表达并减弱其与靶基因结合活性.镧可抑制LPS诱导的IκBα降解,但LPS诱导IKKβ磷酸化不能为镧所阻断,且p-IKKβ磷酸化IκBα的能力亦未受到镧的影响.结论 镧可通过抑制LPS激活巨噬细胞IκBα蛋白降解、p65蛋白核易位及与靶基因结合,从而抑制LPS诱导NF-κB信号通路的活化,这可能是镧抑制LPS活化NF-κB通路分子机制之一.

Objective To study the molecular mechanism of lanthanum on blocking lipopolysaccharide（LPS）-mediated activation of nuclear factor-kappaB （NF-κB）signaling in macrophages.Methods The RAW264.7 macrophages were cultured routinely and divided into 4 groups randomly：LaCl3 ＋LPS group,LPS group,LaCl3 group and control group.The nuclear translocation of p65 protein was detected by immunocytochemistry.Total,cytoplasmic and nuclear proteins were extracted respectively,and then the binding activity of p65 with the target gene was measured by ELISA.Western blot assays were also performed to detect the expression levels of the proteins,including nuclear p65,IκBα and IKK kinase,the phosphorylation status of IκBα and IKK kinase.Results Lanthanum can block LPS-induced activation of p65 protein through various ways,such as inhibiting its nuclear translocation,reducing its expression in the nuclei and decreasing its binding activity with the target genes.Lanthanum inhibited the degradation of LPS-induced IκBα,but the phosphorylation of LPS-induced IKKβ can not be blocked by lanthanum,nor did the phosphorylation ability of p-IKKβ on IκBα.Conclusion Lanthanum inhibited the degradation of IκBα,nuclei translocation of p65 protein and its binding activity with the target genes,thereby inhibited LPS-induced NFκB activation,which might be one of the inhibition mechanisms of lanthanum on nuclear activation.