Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA.
Plant J. 2011 Feb;65(4):634-46. doi: 10.1111/j.1365-313X.2010.04449.x. Epub 2011 Jan 10.
Brassinosteroids (BRs) are important regulators for plant growth and development. BRs signal to control the activities of the BES1 and BZR1 family transcription factors. The transcriptional network through which BES1 and BZR regulate large number of target genes is mostly unknown. By combining chromatin immunoprecipitation coupled with Arabidopsis tiling arrays (ChIP-chip) and gene expression studies, we have identified 1609 putative BES1 target genes, 404 of which are regulated by BRs and/or in gain-of-function bes1-D mutant. BES1 targets contribute to BR responses and interactions with other hormonal or light signaling pathways. Computational modeling of gene expression data using Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNe) reveals that BES1-targeted transcriptional factors form a gene regulatory network (GRN). Mutants of many genes in the network displayed defects in BR responses. Moreover, we found that BES1 functions to inhibit chloroplast development by repressing the expression of GLK1 and GLK2 transcription factors, confirming a hypothesis generated from the GRN. Our results thus provide a global view of BR regulated gene expression and a GRN that guides future studies in understanding BR-regulated plant growth.
油菜素内酯（BRs）是植物生长和发育的重要调节剂。BR 信号控制 BES1 和 BZR1 家族转录因子的活性。BES1 和 BZR 调节大量靶基因的转录网络在很大程度上是未知的。通过结合染色质免疫沉淀与拟南芥平铺阵列（ChIP-chip）和基因表达研究，我们已经鉴定出 1609 个假定的 BES1 靶基因，其中 404 个受 BR 和/或功能获得型 bes1-D 突变体的调节。BES1 靶基因有助于 BR 反应以及与其他激素或光照信号通路的相互作用。使用用于重建精确细胞网络的算法（ARACNe）对基因表达数据进行的计算建模表明，BES1 靶向转录因子形成基因调控网络（GRN）。该网络中的许多基因的突变体在 BR 反应中显示出缺陷。此外，我们发现 BES1 通过抑制 GLK1 和 GLK2 转录因子的表达来抑制叶绿体发育，从而证实了从 GRN 中产生的一个假设。因此，我们的研究结果提供了 BR 调节基因表达的全局视图和一个 GRN，这为未来研究 BR 调节的植物生长提供了指导。
