Kaneto H, Fujii J, Myint T, Miyazawa N, Islam K N, Kawasaki Y, Suzuki K, Nakamura M, Tatsumi H, Yamasaki Y, Taniguchi N
Department of Biochemistry, Osaka University Medical School, Japan.
Biochem J. 1996 Dec 15;320 ( Pt 3)(Pt 3):855-63. doi: 10.1042/bj3200855.
Several reducing sugars brought about apoptosis in isolated rat pancreatic islet cells and in the pancreatic beta-cell-derived cell line HIT. This apoptosis was characterized biochemically by inter-nucleosomal DNA cleavage and morphologically by nuclear shrinkage, chromatin condensation and apoptotic body formation. N-Acetyl-L-cysteine, an antioxidant, and aminoguanidine, an inhibitor of the glycation reaction, inhibited this apoptosis. We also showed directly that proteins in beta-cells were actually glycated by using an antibody which can specifically recognize proteins glycated by fructose, but not by glucose. Furthermore, fluorescence-activated cell sorting analysis using dichlorofluorescein diacetate showed that reducing sugars increased intracellular peroxide levels prior to the induction of apoptosis. Levels of carbonyl, an index of oxidative modification, and of malondialdehyde, a lipid peroxidation product, were also increased. Taken together, these results suggest that reducing sugars trigger oxidative modification and apoptosis in pancreatic beta-cells by provoking oxidative stress mainly through the glycation reaction, which may explain the deterioration of beta-cells under conditions of diabetes.
几种还原糖可诱导大鼠分离胰岛细胞及胰腺β细胞系HIT发生凋亡。这种凋亡在生化方面表现为核小体间DNA裂解，在形态学上表现为细胞核缩小、染色质浓缩及凋亡小体形成。抗氧化剂N-乙酰-L-半胱氨酸及糖基化反应抑制剂氨基胍可抑制这种凋亡。我们还通过使用一种能特异性识别果糖糖基化而非葡萄糖糖基化蛋白质的抗体，直接证实了β细胞中的蛋白质确实发生了糖基化。此外，使用二氯荧光素二乙酸酯进行的荧光激活细胞分选分析表明，还原糖在诱导凋亡之前会增加细胞内过氧化物水平。氧化修饰指标羰基及脂质过氧化产物丙二醛的水平也升高。综合这些结果表明，还原糖主要通过糖基化反应引发氧化应激，从而触发胰腺β细胞的氧化修饰和凋亡，这可能解释了糖尿病条件下β细胞的恶化情况。
