Brain Korea 21 Project for Medical Science, Seoul 120-752, Korea.
Endocrinology. 2013 Aug;154(8):2626-39. doi: 10.1210/en.2013-1031. Epub 2013 May 22.
Growing evidence suggests that advanced glycation end-products (AGEs) are cytotoxic to pancreatic β-cells. The aims of this study were to investigate whether glycated albumin (GA), an early precursor of AGEs, would induce dysfunction in pancreatic β-cells and to determine which kinds of cellular mechanisms are activated in GA-induced β-cell apoptosis. Decreased viability and increased apoptosis were induced in INS-1 cells treated with 2.5 mg/mL GA under 16.7mM high-glucose conditions. Insulin content and glucose-stimulated secretion from isolated rat islets were reduced in 2.5 mg/mL GA-treated cells. In response to 2.5 mg/mL GA in INS-1 cells, autophagy induction and flux decreased as assessed by green fluorescent protein-microtubule-associated protein 1 light chain 3 dots, microtubule-associated protein 1 light chain 3-II conversion, and SQSTM1/p62 in the presence and absence of bafilomycin A1. Accumulated SQSTM1/p62 through deficient autophagy activated the nuclear factor-κB (p65)-inducible nitric oxide synthase-caspase-3 cascade, which was restored by treatment with small interfering RNA against p62. Small interfering RNA treatment against autophagy-related protein 5 significantly inhibited the autophagy machinery resulting in a significant increase in iNOS-cleaved caspase-3 expression. Treatment with 500μM 4-phenyl butyric acid significantly alleviated the expression of endoplasmic reticulum stress markers and iNOS in parallel with upregulated autophagy induction. However, in the presence of bafilomycin A1, the decreased viability of INS-1 cells was not recovered. Glycated albumin, an early precursor of AGE, caused pancreatic β-cell death by inhibiting autophagy induction and flux, resulting in nuclear factor-κB (p65)-iNOS-caspase-3 cascade activation as well as by increasing susceptibility to endoplasmic reticulum stress and oxidative stress.
越来越多的证据表明，糖基化终产物（AGEs）对胰岛β细胞具有细胞毒性。本研究旨在探讨糖化白蛋白（GA）作为AGE 的早期前体是否会引起胰岛β细胞功能障碍，并确定 GA 诱导的β细胞凋亡中激活了哪些细胞机制。在 16.7mM 高葡萄糖条件下，浓度为 2.5mg/mL 的 GA 处理 INS-1 细胞后，细胞活力降低，细胞凋亡增加。用 2.5mg/mL GA 处理的细胞中，胰岛素含量和葡萄糖刺激的大鼠胰岛分泌减少。在 INS-1 细胞中，用 2.5mg/mL GA 处理时，通过绿色荧光蛋白-微管相关蛋白 1 轻链 3 点、微管相关蛋白 1 轻链 3-II 转化和 SQSTM1/p62 的存在和不存在情况下，自噬诱导和通量降低，在用巴弗洛霉素 A1 处理后。由于自噬缺陷导致 SQSTM1/p62 积累，激活了核因子-κB（p65）诱导型一氧化氮合酶-半胱氨酸蛋白酶-3 级联反应，用 p62 的小干扰 RNA 处理可恢复该级联反应。用自噬相关蛋白 5 的小干扰 RNA 处理可显著抑制自噬机制，导致 iNOS 切割的半胱氨酸蛋白酶-3 表达显著增加。用 500μM 4-苯丁酸处理可显著减轻内质网应激标志物和 iNOS 的表达，同时上调自噬诱导。然而，在用巴弗洛霉素 A1 处理时，INS-1 细胞的活力降低并没有恢复。糖化白蛋白作为 AGE 的早期前体，通过抑制自噬诱导和通量导致核因子-κB（p65）-iNOS-半胱氨酸蛋白酶-3 级联激活以及增加对内质网应激和氧化应激的敏感性，引起胰岛β细胞死亡。
