Department of Botany and Plant Sciences, Center for Plant Cell Biology (CEPCEB), Institute of Integrative Genome Biology (IIGB), University of California, Riverside, CA 92521, USA.
Mol Syst Biol. 2013;9:654. doi: 10.1038/msb.2013.8.
In animal systems, master regulatory transcription factors (TFs) mediate stem cell maintenance through a direct transcriptional repression of differentiation promoting TFs. Whether similar mechanisms operate in plants is not known. In plants, shoot apical meristems serve as reservoirs of stem cells that provide cells for all above ground organs. WUSCHEL, a homeodomain TF produced in cells of the niche, migrates into adjacent cells where it specifies stem cells. Through high-resolution genomic analysis, we show that WUSCHEL represses a large number of genes that are expressed in differentiating cells including a group of differentiation promoting TFs involved in leaf development. We show that WUS directly binds to the regulatory regions of differentiation promoting TFs; KANADI1, KANADI2, ASYMMETRICLEAVES2 and YABBY3 to repress their expression. Predictions from a computational model, supported by live imaging, reveal that WUS-mediated repression prevents premature differentiation of stem cell progenitors, being part of a minimal regulatory network for meristem maintenance. Our work shows that direct transcriptional repression of differentiation promoting TFs is an evolutionarily conserved logic for stem cell regulation.
在动物系统中，主调控转录因子（TFs）通过直接转录抑制促进分化的 TFs 来介导干细胞的维持。在植物中是否存在类似的机制尚不清楚。在植物中，茎尖分生组织作为干细胞的储库，为地上所有器官提供细胞。WUSCHEL 是一种在家域 TF 中产生的，位于分生组织细胞中的一个龛位，它迁移到相邻的细胞中，在那里指定干细胞。通过高分辨率基因组分析，我们表明 WUSCHEL 抑制了大量在分化细胞中表达的基因，包括一组参与叶片发育的促进分化的 TFs。我们表明 WUS 直接与促进分化的 TF 的调节区域结合，从而抑制其表达。KANADI1、KANADI2、ASYMMETRICLEAVES2 和 YABBY3。一个计算模型的预测，得到活体成像的支持，表明 WUS 介导的抑制作用防止了干细胞前体的过早分化，是维持分生组织的最小调节网络的一部分。我们的工作表明，直接转录抑制促进分化的 TFs 是干细胞调控的一种进化保守的逻辑。
