Gordon Sean P, Chickarmane Vijay S, Ohno Carolyn, Meyerowitz Elliot M
Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 2009 Sep 22;106(38):16529-34. doi: 10.1073/pnas.0908122106. Epub 2009 Aug 26.
A central unanswered question in stem cell biology, both in plants and in animals, is how the spatial organization of stem cell niches are maintained as cells move through them. We address this question for the shoot apical meristem (SAM) which harbors pluripotent stem cells responsible for growth of above-ground tissues in flowering plants. We find that localized perception of the plant hormone cytokinin establishes a spatial domain in which cell fate is respecified through induction of the master regulator WUSCHEL as cells are displaced during growth. Cytokinin-induced WUSCHEL expression occurs through both CLAVATA-dependent and CLAVATA-independent pathways. Computational analysis shows that feedback between cytokinin response and genetic regulators predicts their relative patterning, which we confirm experimentally. Our results also may explain how increasing cytokinin concentration leads to the first steps in reestablishing the shoot stem cell niche in vitro.
在植物和动物的干细胞生物学中，一个核心的未解决问题是，当细胞在干细胞微环境中移动时，这些微环境的空间组织是如何维持的。我们针对茎尖分生组织（SAM）解决了这个问题，茎尖分生组织中含有多能干细胞，负责开花植物地上组织的生长。我们发现，植物激素细胞分裂素的局部感知建立了一个空间域，在这个空间域中，随着细胞在生长过程中发生位移，通过诱导主调控因子WUSCHEL来重新指定细胞命运。细胞分裂素诱导的WUSCHEL表达通过CLAVATA依赖和CLAVATA非依赖途径发生。计算分析表明，细胞分裂素反应与遗传调控因子之间的反馈预测了它们的相对模式，我们通过实验证实了这一点。我们的结果还可能解释了增加细胞分裂素浓度如何导致在体外重新建立茎干细胞微环境的第一步。
