A genomic approach to identify regulatory nodes in the transcriptional network of systemic acquired resistance in plants.
A genomic approach to identify regulatory nodes in the transcriptional network of systemic acquired resistance in plants.
复制标题
DOI：
10.1371/journal.ppat.0020123
复制
发表时间：
2006-11
期刊：
影响因子：
6.7
通讯作者：
Dong, Xinnian
中科院分区：
文献类型：
--
作者：
Wang, Dong;Amornsiripanitch, Nita;Dong, Xinnian
许多生物过程是由复杂的转录调节因子网络控制的。随着微阵列技术的发展，可以在全基因组水平上检查转录变化。然而，这种分析通常缺乏给定系统的组件之间的层次关系的信息。系统获得性抗性（SAR）是一种诱导型植物防御反应，涉及水杨酸通过转录辅因子 NPR1 诱导的一系列转录事件。为了确定 SAR 网络中的其他调控节点，我们对表达 NPR1-GR（糖皮质激素受体）融合蛋白的拟南芥植物进行了微阵列分析。由于 NPR1-GR 的核转位需要地塞米松，因此我们能够控制 NPR1 依赖性转录并识别 NPR1 的直接转录靶标。我们发现 NPR1 直接上调八个 WRKY 转录因子基因的表达。这个由 74 个转录因子组成的大家族与各种防御反应有关，但尚未将特定的 WRKY 因子放入 SAR 网络中。 NPR1 调节的 WRKY 因子的鉴定使我们能够对少量 WRKY 因子进行深入的遗传分析，并测试与 NPR1 相关的单突变体和双突变体的明确表型。在这些 WRKY 因素中，我们发现了 SAR 的正向和负向调节因子。这种基因组学指导的方法在 SAR 复杂的转录调控网络中明确定位了 5 个 WRKY 因子。我们的工作不仅发现了 SAR 信号网络中新的转录调控元件，而且还证明大基因家族的功能研究必须考虑序列相似性以及候选基因的表达模式。许多生物过程是由复杂的基因表达调控网络控制的。识别这些网络中的调控节点并理解它们之间的层次关系对于我们理解生物系统至关重要。然而，这项任务经常受到这些过程的内在复杂性的阻碍。在这里，作者对植物免疫反应（称为系统获得性抗性）使用了一种受控转录分析策略，一次研究一个转录事件。转录调节蛋白 NPR1 诱导数千个基因，从而激活系统获得性抗性。作者发现 NPR1 的下游是几个由来自转录因子大家族的成员组成的调节节点。破坏这些调控节点会损害 NPR1 的各种功能，从而提供构建基因调控网络所需的信息。
Many biological processes are controlled by intricate networks of transcriptional regulators. With the development of microarray technology, transcriptional changes can be examined at the whole-genome level. However, such analysis often lacks information on the hierarchical relationship between components of a given system. Systemic acquired resistance (SAR) is an inducible plant defense response involving a cascade of transcriptional events induced by salicylic acid through the transcription cofactor NPR1. To identify additional regulatory nodes in the SAR network, we performed microarray analysis on Arabidopsis plants expressing the NPR1-GR (glucocorticoid receptor) fusion protein. Since nuclear translocation of NPR1-GR requires dexamethasone, we were able to control NPR1-dependent transcription and identify direct transcriptional targets of NPR1. We show that NPR1 directly upregulates the expression of eight WRKY transcription factor genes. This large family of 74 transcription factors has been implicated in various defense responses, but no specific WRKY factor has been placed in the SAR network. Identification of NPR1-regulated WRKY factors allowed us to perform in-depth genetic analysis on a small number of WRKY factors and test well-defined phenotypes of single and double mutants associated with NPR1. Among these WRKY factors we found both positive and negative regulators of SAR. This genomics-directed approach unambiguously positioned five WRKY factors in the complex transcriptional regulatory network of SAR. Our work not only discovered new transcription regulatory components in the signaling network of SAR but also demonstrated that functional studies of large gene families have to take into consideration sequence similarity as well as the expression patterns of the candidates. Many biological processes are controlled by intricate regulatory networks of gene expression. Identifying the regulatory nodes in these networks and understanding the hierarchical relationship between them are vital to our understanding of biological systems. However, this task is frequently hampered by the intrinsic complexity of these processes. Here, the authors used a controlled transcriptional profiling strategy to a plant immune response called systemic acquired resistance to study the transcriptional events one at a time. Systemic acquired resistance is activated through the induction of thousands of genes by the transcriptional regulator protein NPR1. The authors found that downstream of NPR1 are several regulatory nodes comprised of members from a large family of transcriptional factors. Disrupting these regulatory nodes compromised various functions assigned to NPR1, providing the information needed to construct a gene regulation network.