α-生育酚抑制高糖诱导大鼠系膜细胞AP-1活性及TGF β1表达

目的　研究α 生育酚对高糖诱导肾小球系膜细胞转录激活蛋白 1(AP 1)和转化生长因子 β1(TGF β1)的影响 ,探讨抗氧化剂治疗糖尿病肾病的机制。方法　采用凝胶迁移率实验 (Gelshiftassay)和超迁移率实验(Gelsupershiftassay)检测不同浓度及不同时间下葡萄糖对系膜细胞AP 1活性的影响、AP 1二聚体中Jun和Fos成分的变化、Western杂交检测TGF β1蛋白表达水平以及抗氧化剂α 生育酚对上述指标的影响。结果　高糖呈浓度和时间依赖性激活系膜细胞AP 1活性 ,AP 1二聚体中JunD、Fos参与这一作用。同时 ,葡萄糖增加系膜细胞TGF β1蛋白表达。加入α 生育酚预处理系膜细胞后 ,葡萄糖诱导的AP 1活性和TGF β1表达水平降低。结论　α 生育酚抑制高糖诱导的系膜细胞AP 1活性及TGF β1表达可能是其作为抗氧化剂治疗糖尿病肾病的分子机制之一

α-Tocopherol Inhibits Activator Protein-1 Binding and TGF-β1 Expression Induced by High Glucose in Rat Mesangial Cells

Purpose　To study the effects of α-tocopherol on activator protein-1(AP-1)binding and TGF-β1 expression induced by high glucose in rat mesangial cells and further to clarify the molecular mechanism of antioxidant in treating diabetic nephropathy.　Methods　AP-1 binding of the rat mesangial cells exposed to high glucose was detected by gel shift assay.The Jun,Fos compositions of AP-1 dimer were determined by supershift assay.Protein expression of TGF-β1 was detected by Western blot.Additionally,the effects of α-tocopherol on AP-1 binding and TGF-β1 expression induced by glucose in rat mesangial cells were also studied.　Results　High glucose stimulated AP-1 binding of mesangial cells in time-and-dose-dependent manners .This AP-1 binding increase involved JunD and Fos as shown by gel supershift.Glucose also increased protein expression of TGF-β1 at same time.The increased AP-1 binding and TGF-β1 were inhibited with pretreatment with α-tocopherol in glucose-treated mesangial cells.　Conclusions　This study suggests that α-tocopherol can significantly inhibit AP-1 activity and TGF-β1 expression by glucose in rat mesangial cells,which may be one of its antioxidation mechanisms to retard diabetic nephropathy.