Glutathione levels and sensitivity to apoptosis are regulated by changes in transaldolase expression
Glutathione levels and sensitivity to apoptosis are regulated by changes in transaldolase expression
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DOI：
10.1074/jbc.271.51.32994
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发表时间：
1996-12-20
影响因子：
4.8
通讯作者：
Perl, A
中科院分区：
文献类型：
--
作者：
Banki, K;Hutter, E;Perl, A
转醛缩酶（TAL）是戊糖磷酸途径（PPP）可逆非氧化分支的关键酶，负责产生NADPH以维持谷胱甘肽处于还原状态（GSH），从而保护细胞完整性免受活性氧中间体（roi）的侵害。roi的形成与某些类型的凋亡细胞死亡有关。为了评估TAL在这一过程中的作用，我们以正义或反义方向的TAL表达载体永久转染Jurkat人T细胞，结果表明，TAL过表达导致葡萄糖6-磷酸脱氢酶和6-磷酸葡萄糖酸脱氢酶活性降低，NADPH和GSH水平降低，使这些细胞对血清剥夺、过氧化氢、一氧化氮、肿瘤坏死因子- α、抗fas单克隆抗体。此外，TAL水平降低导致葡萄糖6-磷酸脱氢酶和6-磷酸葡萄糖酸脱氢酶活性升高，GSH水平升高，并抑制所有五种模型系统的凋亡。TAL表达通过调节PPP和GSH的产生对细胞凋亡易感性的影响与在所测试的每条通路中roi的参与是一致的。通过使用氧化敏感荧光探针测量细胞内ROI的产生，通过GSH前体、n-乙酰半胱氨酸、自由基自旋陷阱5,5-二甲基-1-吡咯啉-1-氧化物和3,3,5,5-四甲基-1-吡咯啉-1-氧化物、抗氧化剂去铁胺、去二氢木脂酸和阿米tal的保护作用，以及通过丁硫氨酸亚胺对GSH消耗的增强作用，进一步证实了pasi介导的细胞死亡中ROI的产生。结果提供了明确的证据，表明TAL在调节PPP两个分支之间的平衡及其通过GSH产生测量的总输出中发挥作用，从而影响对细胞死亡信号的敏感性。
Transaldolase (TAL) is a key enzyme of the reversible nonoxidative branch of the pentose phosphate pathway (PPP) that is responsible for the generation of NADPH to maintain glutathione at a reduced state (GSH) and, thus, to protect cellular integrity from reactive oxygen intermediates (ROIs). Formation of ROIs have been implicated in certain types of apoptotic cell death. To evaluate the role of TAL in this process, Jurkat human T cells were permanently transfected with TAL expression vectors oriented in the sense or antisense direction, Overexpression of TAL resulted in a decrease in glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities and NADPH and GSH levels and rendered these cells highly susceptible to apoptosis induced by serum deprivation, hydrogen peroxide, nitric oxide, tumor necrosis factor-alpha, and anti-Fas monoclonal antibody. In addition, reduced levels of TAL resulted in increased glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities and increased GSH levels with inhibition of apoptosis in all five model systems. The effect of TAL expression on susceptibility to apoptosis through regulating the PPP and GSH production is consistent with an involvement of ROIs in each pathway tested. Production of ROIs in Pas-mediated cell death was further substantiated by measurement of intracellular ROI production with oxidation-sensitive fluorescent probes, by the protective effects of GSH precursor, N-acetyl cysteine, free radical spin traps 5,5-dimethyl-1-pyrroline-1-oxide and 3,3,5,5-tetramethyl-1-pyrroline-1-oxide, the antioxidants desferrioxamine, nordihydroguaiaretic acid, and Amytal, and by the enhancing effects of GSH depletion with buthionine sulfoximine, The results provide definitive evidence that TAL has a role in regulating the balance between the two branches of PPP and its overall output as measured by GSH production and thus influences sensitivity to cell death signals.