Juglone inactivates cysteine-rich proteins required for progression through mitosis
Juglone inactivates cysteine-rich proteins required for progression through mitosis
复制标题
DOI：
10.1074/jbc.m710264200
复制
发表时间：
2008-08-01
影响因子：
4.8
通讯作者：
van der Sluijs, Peter
中科院分区：
文献类型：
--
作者：
Fila, Claudia;Metz, Corina;van der Sluijs, Peter
parvulin肽基脯氨酸异构酶Pin1催化p(S/T)-P键的顺反异构化，并可能改变客户蛋白的构象和功能。由于蛋白磷酸酶2A （PP2A）偏爱p(S/T)-P键的反式构象，因此Pin1可能促进PP2A介导的去磷酸化。核桃酮不可逆地抑制parvulins，经常被用来研究Pin1在体内的功能。该药物阻止有丝分裂磷酸化蛋白的去磷酸化，可能是因为它们结合Pin1并被PP2A去磷酸化。然而，我们在这里显示，核桃酮抑制有丝分裂后的去磷酸化和有丝分裂的退出，独立于Pin1。这种效应涉及中期/后期转变所必需的蛋白质中巯基的共价修饰。特别是具有高半胱氨酸含量的细胞质蛋白易受该药物的影响。巯基的烷基化改变了这些蛋白的构象，微管蛋白和有丝分裂检查点成分BubR1上抗体表位的消失证明了这一点。后者激活后期促进复合物/环小体，降解调节蛋白，如细胞周期蛋白B1和安全蛋白，这是有丝分裂退出所必需的。事实上，核素处理的细胞不能组装有丝分裂纺锤体，这与微管动力学紊乱、免疫检测微管蛋白的丧失和微管蛋白聚集体的形成有关。Juglone还能独立于mps1控制的有丝分裂纺锤体检查点，阻止细胞周期蛋白B1的降解。由于核桃酮在多个水平上影响细胞周期进程，因此需要开发更特异性的药物来研究Pin1在体内的功能。
The parvulin peptidyl-prolyl isomerase Pin1 catalyzes cis-trans isomerization of p(S/T)-P bonds and might alter conformation and function of client proteins. Since the trans conformation of p(S/T)-P bonds is preferred by protein phosphatase 2A (PP2A), Pin1 may facilitate PP2A-mediated dephosphorylation. Juglone irreversibly inhibits parvulins and is often used to study the function of Pin1 in vivo. The drug prevents dephosphorylation of mitotic phosphoproteins, perhaps because they bind Pin1 and are dephosphorylated by PP2A. We show here however that juglone inhibited post-mitotic dephosphorylation and the exit of mitosis, independent of Pin1. This effect involved covalent modification of sulfhydryl groups in proteins essential for metaphase/anaphase transition. Particularly cytoplasmic proteins with a high cysteine content were vulnerable to the drug. Alkylation of sulfhydryl groups altered the conformation of such proteins, as evidenced by the disappearance of antibody epitopes on tubulin and the mitotic checkpoint component BubR1. The latter activates the anaphase-promoting complex/cyclosome, which degrades regulatory proteins, such as cyclin B1 and securins, and is required for mitotic exit. Indeed, juglone-treated cells failed to assemble a mitotic spindle, which correlated with perturbed microtubule dynamics, loss of immunodetectable tubulin, and formation of tubulin aggregates. Juglone also prevented degradation of cyclin B1, independently of the Mps1-controlled mitotic spindle checkpoint. Since juglone affected cell cycle progression at several levels, more specific drugs need to be developed for studies of Pin1 function in vivo.