Redox-regulation of ERK 1/2-directed phosphatase by reactive oxygen species: Role in signaling TPA-induced growth arrest in ML-1 cells
Redox-regulation of ERK 1/2-directed phosphatase by reactive oxygen species: Role in signaling TPA-induced growth arrest in ML-1 cells
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DOI：
10.1002/jcp.21403
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发表时间：
2008-07-01
影响因子：
5.6
通讯作者：
Trush, Michael A.
中科院分区：
文献类型：
--
作者：
Traore, Kassim;Sharma, Rajni;Trush, Michael A.
细胞外信号调节激酶（Erk）12活性发出由12-O-十四烷酰基-佛波醇-13-乙酸酯（TPA）诱导的髓样细胞分化的信号。以前，我们报道了TPA诱导的Erk 1/2激活（磷酸化）需要活性氧（ROS）作为第二信使。在这里，我们假设，响应TPA产生的ROS抑制Erk 1/2-定向磷酸酶活性，这导致Erk 1/2磷酸化增加到信号p21（WAFI/Cip 1）介导的ML-1细胞生长停滞。用TPA孵育ML-1细胞导致磷酸化Erk 1/2的显著积累，并且随后产生H2 O2。有趣的是，TPA处理后，用N-乙酰半胱氨酸（NAC）刺激了一个显着的和快速的去磷酸化的Erk 1/2，这表明再生的Erk 1/2-定向磷酸酶活性的NAC。基于以下观察结果，TPA诱导ML-1细胞中活性氧的产生被认为发生在线粒体电子传递链（METC）中：（i）未分化的ML-1细胞不仅缺乏p67-phox，而且表达NADPH氧化酶酶活性所需的低水平的p47-phox关键组分，（ii）用DPI（一种NADH和NADPH依赖性酶的抑制剂）或大黄酸预处理，复合物1的抑制剂，阻断了ROS的产生，和（iii）微阵列分析数据和蛋白质印迹分析数据的检查揭示了响应于TPA在mRNA和蛋白质水平上的MnSOD表达的诱导。MnSOD是线粒体防御系统中的一个重要成员。总之，这项研究表明，TPA刺激ROS产生作为第二信使激活Erk 1/2通过氧化还原介导的抑制Erk 1/2-定向磷酸酶在ML-I细胞。
Extracellular signal-regulated kinase (Erk) 1/2 activity signals myeloid cell differentiation induced by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Previously, we reported that Erk 1/2 activation (phosphorylation) induced by TPA required reactive oxygen species (ROS) as a second messenger. Here, we hypothesized that ROS generated in response to TPA inhibit Erk 1/2-directed phosphatase activity, which leads to an increase phosphorylation of Erk 1/2 to signal p21(WAFI/Cip1) mediated growth arrest in ML-1 cells. Incubation of ML-1 cells with TPA resulted in a marked accumulation of phosphorylated Erk 1/2, and is subsequent to H2O2 generation. Interestingly, post-TPA-treatment with N-acetylcysteine (NAC) stimulated a marked and a rapid dephosphorylation of Erk 1/2, suggesting a regeneration of Erk 1/2-directed phospahatase activity by NAC. ROS generation in ML-1 cells induced by TPA was suggested to occur in the mitochondrial electron transport chain (METC) based on the following observations: (i) undifferentiated ML-1 cells not only lack p67-phox and but also express a low level of p47-phox key components required for NADPH oxidase enzymatic activity, (ii) pretreatment with DPI, an inhibitor of NADH- and NADPH-dependent enzymes, or rhein, an inhibitor of complex 1, blocked the ROS generation, and (iii) examination of the microarray analysis data and Western blot analysis data revealed an induction of MnSOD expression at both mRNA and protein levels in response to TPA. MnSOD is a key member of the mitochondrial defense system against mitochondrial-derived superoxide. Together, this study suggested that TPA stimulated ROS generation as a second messenger to activate Erk 1/2 via a redox-mediated inhibition of Erk 1/2-directed phosphatase in ML-I cells.