CR-UK Stress Response Laboratory, Biomedical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, UK.
J Biol Chem. 2010 Aug 20;285(34):25928-40. doi: 10.1074/jbc.M110.117911. Epub 2010 Jun 11.
MAPK phosphatase-1 (DUSP1/MKP-1) is a mitogen and stress-inducible dual specificity protein phosphatase, which can inactivate all three major classes of MAPK in mammalian cells. DUSP1/MKP-1 is implicated in cellular protection against a variety of genotoxic insults including hydrogen peroxide, ionizing radiation, and cisplatin, but its role in the interplay between different MAPK pathways in determining cell death and survival is not fully understood. We have used pharmacological and genetic tools to demonstrate that DUSP1/MKP-1 is an essential non-redundant regulator of UV-induced cell death in mouse embryo fibroblasts (MEFs). The induction of DUSP1/MKP-1 mRNA and protein in response to UV radiation is mediated by activation of the p38alpha but not the JNK1 or JNK2 MAPK pathways. Furthermore, we identify MSK1 and -2 and their downstream effectors cAMP-response element-binding protein/ATF1 as mediators of UV-induced p38alpha-dependent DUSP1/MKP-1 transcription. Dusp1/Mkp-1 null MEFs display increased signaling through both the p38alpha and JNK MAPK pathways and are acutely sensitive to UV-induced apoptosis. This lethality is rescued by the reintroduction of wild-type DUSP1/MKP-1 and by a mutant of DUSP1/MKP-1, which is unable to bind to either p38alpha or ERK1/2, but retains full activity toward JNK. Importantly, whereas small interfering RNA-mediated knockdown of DUSP1/MKP-1 sensitizes wild-type MEFs to UV radiation, DUSP1/MKP-1 knockdown in MEFS lacking JNK1 and -2 does not result in increased cell death. Our results demonstrate that cross-talk between the p38alpha and JNK pathways mediated by induction of DUSP1/MKP-1 regulates the cellular response to UV radiation.
丝裂原活化蛋白激酶磷酸酶-1（DUSP1/MKP-1）是一种有丝分裂原和应激诱导的双特异性蛋白磷酸酶，它可以使哺乳动物细胞中的所有三种主要类型的 MAPK 失活。DUSP1/MKP-1 参与细胞对多种遗传毒性刺激的保护，包括过氧化氢、电离辐射和顺铂，但它在不同 MAPK 途径之间的相互作用中在决定细胞死亡和存活中的作用尚未完全阐明。我们使用药理学和遗传学工具证明，DUSP1/MKP-1 是小鼠胚胎成纤维细胞（MEFs）中 UV 诱导细胞死亡的必需非冗余调节剂。DUSP1/MKP-1 mRNA 和蛋白的诱导对 UV 辐射的反应是由 p38alpha 的激活介导的，而不是 JNK1 或 JNK2 MAPK 途径。此外，我们确定 MSK1 和 -2 及其下游效应物 cAMP 反应元件结合蛋白/ATF1 是介导 UV 诱导的 p38alpha 依赖性 DUSP1/MKP-1 转录的介质。Dusp1/Mkp-1 缺失 MEFs 显示出两条信号通路（p38alpha 和 JNK MAPK 通路）信号增强，对 UV 诱导的细胞凋亡非常敏感。这种致死性可以通过引入野生型 DUSP1/MKP-1 和不能与 p38alpha 或 ERK1/2 结合但对 JNK 保持完全活性的 DUSP1/MKP-1 突变体来挽救。重要的是，尽管通过 DUSP1/MKP-1 的小干扰 RNA 敲低使野生型 MEFs 对 UV 辐射敏感，但在缺乏 JNK1 和 -2 的 MEFs 中敲低 DUSP1/MKP-1 不会导致细胞死亡增加。我们的结果表明，由 DUSP1/MKP-1 诱导的 p38alpha 和 JNK 途径之间的串扰调节细胞对 UV 辐射的反应。
