牙龈卟啉单胞菌来源的脂多糖通过X盒结合蛋白1调控脂肪细胞胰岛素信号通路的机制研究

Mechanism of Porphyromonas gingivalis-lipopolysaccharide in regulating the insulin signaling pathway in adipocytes via X-box binding protein 1

目的探讨内质网应激(ERS)关键信号分子X盒结合蛋白1(XBP1)在牙周炎致病菌牙龈卟啉单胞菌(P.gingivalis)来源的脂多糖(LPS)刺激下对脂肪细胞胰岛素信号通路的影响。方法原代培养大鼠脂肪细胞,通过P.gingivalis-LPS(100 ng·mL^(-1))刺激大鼠脂肪细胞4、8、12、24 h,蛋白质印迹法检测胰岛素信号通路胰岛素受体底物-1(IRS-1)、磷酸化磷脂酰肌醇依赖性激酶-1(p-PDK-1)和磷酸化蛋白激酶B(p-AKT)的蛋白表达;再将空载过表达慢病毒(pLVX-NC1)、过表达XBP1慢病毒(pLVX-XBP1)、空载干扰慢病毒(pLVX-NC2)、干扰XBP1慢病毒(pLVX-XBP1-RNAi)分别转染脂肪细胞,通过P.gingivalis-LPS刺激转染后的大鼠脂肪细胞,蛋白质印迹法检测胰岛素信号通路的蛋白表达。结果在P.gingivalis-LPS刺激下,大鼠脂肪细胞的胰岛素信号通路蛋白IRS-1、p-PDK-1、p-AKT表达呈下降趋势,差异有统计学意义(P<0.05);pLVX-XBP1组的IRS-1、p-PDK-1、p-AKT蛋白表达在P.gingivalis-LPS刺激8、12 h后整体高于pLVX-NC1组,差异有统计学意义(P<0.05);pLVX-XBP1-RNAi组在P.gingivalis-LPS刺激4、8、12、24 h后IRS-1、pPDK-1和p-AKT蛋白表达整体低于pLVX-NC2组,差异有统计学意义(P<0.05)。结论P.gingivalis-LPS通过XBP1调控脂肪细胞胰岛素信号通路。

Objective This study aims to investigate the effect of X-box binding protein 1(XBP1),a key signal molecule of ERS,on the insulin signaling pathway in adipocytes stimulated by Porphyromonas gingivalis(P.gingivalis)-lipopolysaccharide(LPS),a pathogenic bacterium of periodontitis.Methods Primary cultured rat adipocytes were stimulated by P.gingivalis-LPS(100 ng·mL^(-1))for 4,8,12,and 24 h.The protein expression levels of insulin receptor substrate-1(IRS-1),phosphoinositide dependent protein kinase(p-PDK-1),and protein kinase B(p-AKT-1)in the insulin signaling pathway were detected by Western blot analysis.pLVX-NC1,pLVX-XBP1,pLVX-NC2,and pLVX-XBP1-RNAi were transfected into adipocytes,respectively.The transfected rat adipocytes were stimulated by P.gingivalis-LPS,and the protein expression of the insulin signaling pathway was detected by Western blot.Results The Western Blot showed decreased protein expression of the insulin signaling pathway in rat adipocytes stimulated with P.gingivalis-LPS compared with the control,and the difference was statistically significant(P<0.05).The protein expression levels of IRS-1,p-PDK-1,and p-AKT in the rat adipocytes of p LVX-XBP1 were significantly higher than those in p LVX-NC1 at 8 and 12 h after P.gingivalis-LPS stimulation(P<0.05).The protein expression levels of IRS-1,p-PDK-1,and p-AKT in the rat adipocytes of p LVX-XBP1-RNAi were significantly lower than those in p LVX-NC2 at 4,8,12,and 24 h after P.gingivalisLPS stimulation(P<0.05).Conclusion P.gingivalis-LPS regulates the insulin signaling pathway in adipocytes through XBP1.