Huang Yan, Liu Jie, Xu Yancheng, Dai Zhe, Alves Martins Hedson
Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
J Huazhong Univ Sci Technolog Med Sci. 2012 Feb;32(1):53-58. doi: 10.1007/s11596-012-0009-7. Epub 2012 Jan 27.
The molecular mechanism by which obesity induces insulin resistance is not completely understood. The aim of this study was to determine how lipopolysaccharide-induced tumor necrosis-α factor (LITAF) influenced obesity-induced insulin resistance using a cellular co-culture system. The cells were divided into 3 groups: palmitic acid (PA) stimulation group, LITAF small interfering RNA (siRNA) group and untreated (NC) group. The LITAF siRNA was used for knockdown of LITAF expression in human THP-1 macrophages. The expression levels of LITAF, IRS-2, IRS-2Tyr465, PI3K, and GLUT2 in each group were measured by using quantitative reverse transcriptase real-time polymerase chain reaction and Western blotting. The expression of LITAF was much higher in the PA group than in the siRNA and NC groups (*P<0.05); meanwhile, the expression of IRS-2, IRS-2Tyr465, PI3K, and GLUT2 was much lower in the PA group than in the NC group (*P<0.05); however, IRS-2, IRS-2Tyr465, PI3K, and GLUT2 had much higher expression in the siRNA group than in the PA group (*P<0.05). It is concluded that PA can induce insulin resistance in liver cells and knockdown of LITAF expression can reduce insulin resistance in liver cells, suggesting LITAF may regulate the insulin signal transduction pathway involved in obesity-induced insulin resistance.
肥胖诱导胰岛素抵抗的分子机制尚未完全明确。本研究旨在利用细胞共培养系统，确定脂多糖诱导的肿瘤坏死-α因子（LITAF）如何影响肥胖诱导的胰岛素抵抗。细胞被分为3组：棕榈酸（PA）刺激组、LITAF小干扰RNA（siRNA）组和未处理（NC）组。LITAF siRNA用于敲低人THP-1巨噬细胞中LITAF的表达。通过定量逆转录实时聚合酶链反应和蛋白质免疫印迹法检测每组中LITAF、胰岛素受体底物-2（IRS-2）、酪氨酸465位点磷酸化的IRS-2（IRS-2Tyr465）、磷脂酰肌醇-3激酶（PI3K）和葡萄糖转运蛋白2（GLUT2）的表达水平。PA组中LITAF的表达远高于siRNA组和NC组（*P<0.05）；同时，PA组中IRS-2、IRS-2Tyr465、PI3K和GLUT2的表达远低于NC组（*P<0.05）；然而，siRNA组中IRS-2、IRS-2Tyr465、PI3K和GLUT2的表达远高于PA组（*P<0.05）。结论是PA可诱导肝细胞胰岛素抵抗，敲低LITAF表达可降低肝细胞胰岛素抵抗，提示LITAF可能调节肥胖诱导的胰岛素抵抗中涉及的胰岛素信号转导通路。
