PKR 通过SUMO化修饰调控胰岛beta细胞P53 功能上调

目的：探讨PKR通过SUMO 化修饰上调P53 功能，阐明胰岛beta细胞增殖抑制的分子机制。方法：转染wt-PKR 质粒并结合 BEPP刺激，诱导PKR在胰岛beta细胞特异性激活。免疫印迹和免疫共沉淀技术检测P53 及P53-SUMO-1 蛋白结合水平变化；并给 予SUMO 化抑制剂Spectomycin B1，分析其相关分子机制。结果：免疫印迹和实时定量PCR 检测表明：PKR 特异激活能诱导P53 蛋白水平而不是mRNA水平上调；免疫共沉淀分析显示：PKR 促进了SUMO-1 与P53 蛋白结合水平的增加；而Spectomycin B1 能抑制PKR 诱导的P53 蛋白水平及其与SUMO 结合的增加。结论：PKR能通过促进P53 的SUMO 化修饰，上调其功能，诱导胰 岛beta细胞增殖抑制，可能参与2 型糖尿病的发生和病程发展。

PKR Upregulate P53 Function through Sumoylation in Pancreatic beta-cell

Objective:To investigate the way that activated PKR induce the upregulation of P53 function in pancreatic beta-cell and the molecular mechanism of the inhibition of the proliferation of pancreatic beta-cell.Methods:Pancreatic beta-cell was transfected with wt-PKR plasmid and treated with BEPP. Western blot and co-immunoprecipitation was performed to detect P53 protein levels and P53-SUMO-1 protein-protein interaction. Sumoylation inhibitor Spectomycin B1 was pretreated to establish negative control group.Results:In PKR overexpressing beta-cells, BEPP induced increase of PKR protein expression but not mRNA expression, and PKR--SUMO-1 protein-protein interaction. Spectomycin B1 inhibited PKR-induced upregulation of P53 sumoylation and protein level.Conclusion:PKR can upregulate the protein level and stability of P53 through P53 sumoylation, involving in pancreatic betacell dysfunction and the mechanismof type 2 diabetes mellitus.