The bHLH genes GL3 and EGL3 participate in an intercellular regulatory circuit that controls cell patterning in the Arabidopsis root epidermis
The bHLH genes GL3 and EGL3 participate in an intercellular regulatory circuit that controls cell patterning in the Arabidopsis root epidermis
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DOI：
10.1242/dev.01565
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发表时间：
2005-01-01
期刊：
影响因子：
4.6
通讯作者：
Schiefelbein, J
中科院分区：
文献类型：
--
作者：
Bernhardt, C;Zhao, MZ;Schiefelbein, J
拟南芥根表皮毛细胞和非毛细胞的特化为植物细胞命运决定的研究提供了一个有用的模型。已知推定的转录调节因子网络，包括相关的bHLH蛋白GLABRA 3（GL 3）和GLABRA 3的增强子（EGL 3），影响这些细胞类型的模式。本文分析了GL 3和EGL 3在根表皮发育过程中的表达和调控。虽然它们被认为在毛细胞和非毛细胞类型中起作用，但我们惊奇地发现GL 3和EGL 3基因表达和RNA积累优先发生在发育中的毛细胞中。通过分析GL 3：：GUS和EGL 3：：GUS报告基因融合体在各种突变体和过表达系中的表达，我们发现这两个基因的表达在发育中的非毛细胞中受WER、GL 3和EGL 3负调控，而在发育中的毛细胞中受CPC和TRY蛋白正调控。此外，在GL 3启动子下表达的GL 3-YFP翻译融合物的分析表明，GL 3蛋白从毛细胞移动到非毛细胞。这些结果表明，N细胞中的GL 3/EGL 3积累依赖于毛细胞命运的特化，已知毛细胞命运本身受到非毛细胞的影响（通过CPC介导的侧向抑制）。这种双向信号机制定义了一种新的细胞间通讯调节回路，以指定表皮细胞类型。
The specification of the hair and non-hair cells in the Arabidopsis root epidermis provides a useful model for the study of cell fate determination in plants. A network of putative transcriptional regulators, including the related bHLH proteins GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), is known to influence the patterning of these cell types. Here, we analyze the expression and regulation of GL3 and EGL3 during root epidermis development. Although they are thought to act in both the hair and non-hair cell types, we surprisingly found that GL3 and EGL3 gene expression and RNA accumulation occurs preferentially in the developing hair cells. By analyzing the expression of GL3::GUS and EGL3::GUS reporter fusions in various mutant and overexpression lines, we discovered that the expression of both genes is negatively regulated by WER, GL3 and EGL3 in the developing non-hair cells, and positively regulated by the CPC and TRY proteins in the developing hair cells. Further, the analysis of a GL3-YFP translational fusion, expressed under the GL3 promoter, indicates that the GL3 protein moves from the hair cells to the non-hair cells. These results suggest that GL3/EGL3 accumulation in the N cells is dependent on specification of the hair cell fate, which itself is known to be influenced (via CPC-mediated lateral inhibition) by the non-hair cells. This bi-directional signaling mechanism defines a new regulatory circuit of intercellular communication to specify the epidermal cell types.