糖尿病和硝化条件下胰岛素受体及底物酪氨酸磷酸化的研究

利用新颖的定量核磁共振(³¹P NMR)法和免疫印迹法研究了四氧嘧啶诱导的糖尿病状态下以及酪氨酸经过氧亚硝酸根供体SIN-1硝化条件下大鼠肝脏胰岛素受体(IR)的自磷酸化和受体底物1(IRS1)的磷酸化。结果表明，四氧嘧啶诱导的糖尿病大鼠肝脏中IR自磷酸化水平削弱了，硝化对大鼠肝脏中IR自磷酸化的影响依赖于SIN-1浓度，根据IRS1磷酸化位点基序设计的多肽的硝化完全抑制了其磷酸化，提示酪氨酸硝化可能干扰胰岛素磷酸化信号通路。

Protein Tyrosine Phosphorylation of the Insulin Receptor and Its Substrate under Diabetes Mellitus and Nitration Conditions

Insulin receptor (IR) autophosphorylation and phosphorylation of the IR substrate-1 (IRS1) was investigated under the conditions of alloxan-induced diabetes and nitration of tyrosine residues after treatment with the peroxynitrite donor SIN-1 in vitro. A novel quantitative ³¹P NMR method based on our previously developed qualitative protocol and western-blotting analysis was used in present research. The results illustrated that IR autophosphorylation levels were decreased in rat livers rendered diabetic by alloxan. After the addition of SIN-1 to purified IR aliquots, a dose-dependent alteration of autophosphorylation levels occurred. This suggested that the effects of the nitration of IR on the autophosphorylation depended on the peroxynitrite concentration. The study on phosphorylation of synthetic peptides with the phosphorylation motif of IRS1 showed that the nitration of tyrosine inhibited the phosphorylation, suggesting that tyrosine nitration might interfere with the phosphorylation in insulin signaling pathways.