Karlsen A E, Pavlovic D, Nielsen K, Jensen J, Andersen H U, Pociot F, Mandrup-Poulsen T, Eizirik D L, Nerup J
Steno Diabetes Center and Hagedorn Research Institute, Gentofte, Denmark.
J Clin Endocrinol Metab. 2000 Feb;85(2):830-6. doi: 10.1210/jcem.85.2.6366.
Whereas nitric oxide (NO) production is associated with the toxic effect of cytokines on rodent pancreatic beta-cells, cytokine-induced apoptosis in human islets may occur independently of NO. The cysteine protease interleukin (IL)-1 converting enzyme (ICE) is a key proapoptotic caspase. Our aim was therefore to analyze the effect of cytokines on ICE expression in human, rat, and mouse islets and rat insulinoma cells. ICE messenger RNA (mRNA) expression was highly up-regulated after 6-, 24-, and 72-h exposure of human islets to interferon (IFN)gamma, tumor necrosis factor (TNF)alpha + IFNgamma or IL-1beta + TNFalpha + IFNgamma, paralleled by increased iNOS (the inducible form of NO synthase) expression and NO production after exposure to the combined cytokines but not to IFNgamma or TNFalpha + IFNgamma. Cytokine-induced NO-independent ICE transcription was confirmed using iNOS inhibitors. Exposure of rat and mouse islets, or rat insulinoma cells, for 24 h to IFNgamma alone or in combination with the two other cytokines also resulted in a highly significant ICE mRNA expression. ICE transcription was not inducible in islets from IFN regulatory factor-1 knock-out mice, suggesting a key-role of this transcription-factor in cytokine-mediated ICE expression in pancreatic islets. In conclusion, cytokines and IFNgamma in particular increase ICE mRNA expression in pancreatic islet cells and beta-cell lines, independently of NO synthesis, suggesting that ICE up-regulation may be involved in cytokine-induced NO-independent apoptosis of human islets.
虽然一氧化氮（NO）的产生与细胞因子对啮齿动物胰腺β细胞的毒性作用有关，但细胞因子诱导的人胰岛细胞凋亡可能独立于NO发生。半胱氨酸蛋白酶白细胞介素（IL）-1转化酶（ICE）是一种关键的促凋亡半胱天冬酶。因此，我们的目的是分析细胞因子对人、大鼠和小鼠胰岛以及大鼠胰岛素瘤细胞中ICE表达的影响。人胰岛在暴露于干扰素（IFN）γ、肿瘤坏死因子（TNF）α + IFNγ或IL-1β + TNFα + IFNγ 6小时、24小时和72小时后，ICE信使核糖核酸（mRNA）表达高度上调，同时在暴露于联合细胞因子后诱导型一氧化氮合酶（iNOS，NO合酶的诱导形式）表达增加和NO产生增加，但暴露于IFNγ或TNFα + IFNγ时则不然。使用iNOS抑制剂证实了细胞因子诱导的不依赖NO的ICE转录。大鼠和小鼠胰岛或大鼠胰岛素瘤细胞单独暴露于IFNγ或与其他两种细胞因子联合暴露24小时也导致ICE mRNA表达高度显著增加。在干扰素调节因子-1基因敲除小鼠的胰岛中，ICE转录不可诱导，这表明该转录因子在细胞因子介导的胰岛ICE表达中起关键作用。总之，细胞因子尤其是IFNγ可增加胰岛细胞和β细胞系中ICE mRNA的表达，独立于NO合成，提示ICE上调可能参与细胞因子诱导的人胰岛不依赖NO的凋亡。
