n nnnMitogen-activated protein kinase (MAPK) signaling networks regulatenumerous eukaryotic biological processes. In Arabidopsis thaliana,signaling networks that contain MAPK kinases MKK4/5 and MAPKsMPK3/6 function in abiotic and biotic stress responses and regulateembryonic and stomatal development. However, how single MAPKmodules direct specific output signals without cross-activatingadditional downstream processes is largely unknown. Studyingrelationships between MAPK components and downstream signalingoutcomes is difficult because broad experimental manipulationof these networks is often lethal or associated with multiplephenotypes. Stomatal development in Arabidopsis follows a seriesof discrete, stereotyped divisions and cell state transitions.By expressing a panel of constitutively active MAPK kinase (MAPKK)variants in discrete stomatal lineage cell types, we identifieda new inhibitory function of MKK4 and MKK5 in meristemoid self-renewaldivisions. Furthermore, we established roles for MKK7 and MKK9as both negative and (unexpectedly) positive regulators duringthe major stages of stomatal development. This has expandedthe number of known MAPKKs that regulate stomatal developmentand allowed us to build plausible and testable subnetworks ofsignals. This in vivo cell type–specific assay can beadapted to study other protein families and thus may revealinsights into other complex signal transduction pathways inplants.展开▼
机译：ABSTRACTn n
n TOP n <字体颜色= 464c53>抽象 n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n n nnnMitogen激活蛋白激酶（MAPK）信号网络调节 众多的真核生物过程。在拟南芥中，包含MAPK激酶MKK4 / 5和MAPKs MPK3 / 6的 信号网络在非生物和生物胁迫响应中起作用并调节 胚胎和气孔发育。但是，单个MAPK 模块如何在不交叉激活 附加下游过程的情况下定向特定输出信号的方式在很大程度上是未知的。研究MAPK成分与下游信号传导 结果之间的关系很困难，因为这些网络的广泛实验操作 通常是致命的或与多个 < / SUP>表型。 拟南芥中的气孔发育遵循一系列离散的，定型的分裂和细胞状态转变。 通过表达一组组成型活性MAPK激酶（MAPKK） 在离散的气孔谱系细胞类型中的变体，我们确定了 对MKK4和MKK5在间质自我更新 区域的新抑制作用。此外，我们确定了MKK7和MKK9 在气孔发育的主要阶段中既是负调节剂，又是（出乎意料的）正调节剂。这扩大了 调节气孔发育的已知MAPKK 的数量，并允许我们构建 信号的可信且可测试的子网。这种体内细胞类型特异性测定法可以适应于研究其他蛋白质家族，从而可以揭示 植物中其他复杂信号转导途径的见解。 。展开▼
