PDF(Pubmed)
Abstract：
Advanced glycated end products (AGEs) are cytotoxic compounds that are mainly increased in diabetes mellitus (DM), kidney failure, inflammation, and in response to the ingestion of AGE-rich diets. AGEs can also impair glycemic homeostasis by decreasing the expression of the Slc2a4 (solute carrier family 2 member 4) gene and its GLUT4 (solute carrier family 2, facilitated glucose transporter member 4) protein in muscle. However, the mechanisms underlying AGE\'s effect on adipocytes have not been demonstrated yet. This study investigated the effects of AGEs upon Slc2a4/GLUT4 expression in 3T3-L1 adipocytes, as well as the potential role of NFKB (nuclear factor NF-kappa-B) activity in the effects observed. Adipocytes were cultured in the presence of control albumin (CA) or advanced glycated albumin (GA) at concentrations of 0.4, 3.6, and 5.4 mg/mL for 24 h or 72 h. Slc2a4, Rela, and Nfkb1mRNAs were measured by RT-qPCR, GLUT4, IKKA/B, and p50/p65 NFKB subunits using Western blotting, and p50/p65 binding into the Slc2a4 promoter was analyzed by chromatin immunoprecipitation (ChIP) assay. GA at 0.4 mg/mL increased Slc2a4/GLUT4 expression after 24 h and 72 h (from 50% to 100%), but at 5.4 mg/mL, Slc2a4/GLUT4 expression decreased at 72 h (by 50%). Rela and Nfkb1 expression increased after 24 h at all concentrations, but this effect was not observed at 72 h. Furthermore, 5.4 mg/mL of GA increased the p50/p65 nuclear content and binding into Slc2a4 at 72 h. In summary, this study reveals AGE-induced and NFKB-mediated repression of Slc2a4/GLUT4 expression. This can compromise the adipocyte glucose utilization, contributing not only to the worsening of glycemic control in DM subjects but also the impairment of glycemic homeostasis in non-DM subjects under the high intake of AGE-rich foods.
摘要：
晚期糖基化终产物（AGEs）是主要在糖尿病（DM）中增加的细胞毒性化合物，肾衰竭,炎症,以及对摄入富含AGE的饮食的反应。AGEs还可以通过降低Slc2a4（溶质载体家族2成员4）基因及其GLUT4（溶质载体家族2，促进葡萄糖转运蛋白成员4）蛋白在肌肉中的表达来损害血糖稳态。然而,AGE对脂肪细胞影响的潜在机制尚未得到证实。这项研究调查了AGEs对3T3-L1脂肪细胞Slc2a4/GLUT4表达的影响，以及NFKB（核因子NF-κB）活性在观察到的作用中的潜在作用。将脂肪细胞在浓度为0.4、3.6和5.4mg/mL的对照白蛋白（CA）或晚期糖化白蛋白（GA）存在下培养24小时或72小时。Slc2a4，Rela，通过RT-qPCR检测Nfkb1mRNA，GLUT4,IKKA/B,和p50/p65NFKB亚基使用蛋白质印迹，通过染色质免疫沉淀(ChIP)测定分析p50/p65与Slc2a4启动子的结合。0.4mg/mL的GA在24小时和72小时后增加了Slc2a4/GLUT4的表达（从50％到100％），但在5.4毫克/毫升时，Slc2a4/GLUT4表达在72h时下降(下降50%)。在所有浓度下，Rela和Nfkb1表达在24小时后增加，但在72小时没有观察到这种效果。此外，5.4mg/mL的GA在72h时增加了p50/p65核含量并结合到Slc2a4中。总之，这项研究揭示了AGE诱导的和NFKB介导的Slc2a4/GLUT4表达的抑制。这可能会损害脂肪细胞葡萄糖的利用，不仅导致DM受试者血糖控制恶化，而且在高摄入富含AGE的食物下，非DM受试者的血糖稳态受损。
