作者:Marni Brisson、Theresa Nguyen、Peter Wipf、Beomjun Joo、Billy W. Day、John S. Skoko、Emanuel M. Schreiber、Caleb Foster、Pallavi Bansal、John S. Lazo
DOI:10.1124/mol.105.016360
日期:2005.12
Intracellular reduction and oxidation pathways regulate protein functionality through both reversible and irreversible mechanisms. The Cdc25 phosphatases, which control cell cycle progression, are potential subjects of oxidative regulation. Many of the more potent Cdc25 phosphatase inhibitors reported to date are quinones, which are capable of redox cycling. Therefore, we used the previously characterized quinolinedione Cdc25 inhibitor DA3003-1 [NSC 663284 or 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione] and a newly synthesized congener JUN1111 [7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione] to test the hypothesis that quinone inhibitors of Cdc25 regulate phosphatase activity through redox mechanisms. Like DA3003-1, JUN1111 selectively inhibited Cdc25 phosphatases in vitro in an irreversible, time-dependent manner and arrested cells in the G1 and G2/M phases of the cell cycle. It is noteworthy that both DA3003-1 and JUN1111 directly inhibited Cdc25B activity in cells. Depletion of glutathione increased cellular sensitivity to DA3003-1 and JUN1111, and in vitro Cdc25B inhibition by these compounds was sensitive to pH, catalase, and reductants (dithiothreitol and glutathione), consistent with oxidative inactivation. In addition, both DA3003-1 and JUN1111 rapidly generated intracellular reactive oxygen species. Analysis of Cdc25B by mass spectrometry revealed sulfonic acid formation on the catalytic cysteine of Cdc25B after in vitro treatment with DA3003-1. These results indicate that irreversible oxidation of the catalytic cysteine of Cdc25B is indeed a mechanism by which these quinolinediones inactivate this protein phosphatase.
细胞内还原和氧化途径通过可逆和不可逆机制调节蛋白质的功能。控制细胞周期进程的 Cdc25 磷酸酶是氧化调节的潜在对象。迄今报道的许多更有效的 Cdc25 磷酸酶抑制剂都是醌类化合物,它们能够进行氧化还原循环。因此,我们使用先前表征的喹啉二酮 Cdc25 抑制剂 DA3003-1 [NSC 663284 或 6-氯-7-(2-吗啉-4-基-乙基氨基)-喹啉-5,8-二酮] 和新合成的同系物 JUN1111 [7-(2-吗啉-4-基-乙基氨基)-喹啉-5,8-二酮] 来检验 Cdc25 的醌类抑制剂通过氧化还原机制调节磷酸酶活性的假设。与 DA3003-1 一样,JUN1111 在体外以不可逆、时间依赖性的方式选择性地抑制 Cdc25 磷酸酶,并使细胞停滞在细胞周期的 G1 和 G2/M 阶段。值得注意的是,DA3003-1 和 JUN1111 都能直接抑制细胞中 Cdc25B 的活性。谷胱甘肽的耗竭增加了细胞对 DA3003-1 和 JUN1111 的敏感性,这些化合物对体外 Cdc25B 的抑制作用对 pH 值、过氧化氢酶和还原剂(二硫苏糖醇和谷胱甘肽)很敏感,这与氧化失活一致。此外,DA3003-1 和 JUN1111 都能迅速产生细胞内活性氧。质谱分析显示,DA3003-1体外处理后,Cdc25B的催化半胱氨酸上形成了磺酸。这些结果表明,Cdc25B 催化半胱氨酸的不可逆氧化确实是这些喹啉二酮类化合物使这种蛋白磷酸酶失活的一种机制。