Popescu Sorina C, Popescu George V, Bachan Shawn, Zhang Zimei, Gerstein Mark, Snyder Michael, Dinesh-Kumar Savithramma P
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
Genes Dev. 2009 Jan 1;23(1):80-92. doi: 10.1101/gad.1740009. Epub 2008 Dec 18.
Signaling through mitogen-activated protein kinases (MPKs) cascades is a complex and fundamental process in eukaryotes, requiring MPK-activating kinases (MKKs) and MKK-activating kinases (MKKKs). However, to date only a limited number of MKK-MPK interactions and MPK phosphorylation substrates have been revealed. We determined which Arabidopsis thaliana MKKs preferentially activate 10 different MPKs in vivo and used the activated MPKs to probe high-density protein microarrays to determine their phosphorylation targets. Our analyses revealed known and novel signaling modules encompassing 570 MPK phosphorylation substrates; these substrates were enriched in transcription factors involved in the regulation of development, defense, and stress responses. Selected MPK substrates were validated by in planta reconstitution experiments. A subset of activated and wild-type MKKs induced cell death, indicating a possible role for these MKKs in the regulation of cell death. Interestingly, MKK7- and MKK9-induced death requires Sgt1, a known regulator of cell death induced during plant innate immunity. Our predicted MKK-MPK phosphorylation network constitutes a valuable resource to understand the function and specificity of MPK signaling systems.
通过丝裂原活化蛋白激酶（MPK）级联进行信号传导是真核生物中一个复杂且基础的过程，这需要MPK激活激酶（MKK）和MKK激活激酶（MKKK）。然而，迄今为止，仅揭示了有限数量的MKK-MPK相互作用以及MPK磷酸化底物。我们确定了拟南芥中的哪些MKK在体内优先激活10种不同的MPK，并使用激活的MPK来探测高密度蛋白质微阵列，以确定它们的磷酸化靶标。我们的分析揭示了包含570个MPK磷酸化底物的已知和新的信号传导模块；这些底物富含参与发育、防御和应激反应调控的转录因子。通过植物体内重组实验验证了选定的MPK底物。一部分激活的和野生型MKK诱导细胞死亡，表明这些MKK在细胞死亡调控中可能发挥作用。有趣的是，MKK7和MKK9诱导的细胞死亡需要Sgt1，Sgt1是植物先天免疫过程中诱导的细胞死亡的已知调节因子。我们预测的MKK-MPK磷酸化网络构成了理解MPK信号系统功能和特异性的宝贵资源。
