Molecular Mechanisms of Stem Cell Homeostasis in Arabidopsis

摘要 在包括动物、植物和人类在内的多细胞生物中，干细胞在以下方面发挥保守作用： 维持自身未分化，但不断分裂以维持器官发育和身体 阵干细胞功能缺陷导致器官发育异常和疾病。在另一边， 解开干细胞行为和调节可以提供有效的基于细胞的疗法，包括组织 再生用于人类疾病，如神经变性、糖尿病和心脏病。迄今为止 控制干细胞小生境的起始、增殖和终止的调节机制仍然不完全 明白在这里，我们建议确定干细胞稳态的细胞和分子基础 以拟南芥茎尖分生组织（SAM）为模型系统。因为未分化的干细胞 拟南芥的自组装膜位于表面或靠近表面，在实验过程中， 非侵入性的延时实时成像方法在拟南芥中特别有效，可以跟踪拟南芥的命运。 每个干细胞及其衍生物，并量化体内细胞动力学。此外， 拟南芥使我们能够定量解剖基因功能，通过使用现有的突变体阵列， 改变了SAM大小和干细胞数量。使用这个系统，通过结合体内的时间推移 共聚焦成像，基因功能的瞬时和稳定扰动，体外生物化学和计算机模拟 量化和建模方法，我们的目标是揭示机制，一小群关键的 转录调节因子，其被排除在干细胞之外，但决定干细胞的身份和活性 在SAM中的细胞。我们的工作不仅将确定尚未找到的分子连接和细胞间通讯 分化和未分化的细胞之间，而且还阐明了细胞非分化的调控网络。 控制干细胞稳态的自主现象。

ABSTRACT In multicellular organisms including animals, plants and human beings, stem cells play conserved roles in maintaining themselves undifferentiated but continuously dividing to sustain organ development and body formation. Defects in stem cell function lead to abnormal organ development and diseases. On the other side, unraveling stem cell behavior and regulation can provide effective cell-based therapies including tissue regeneration for human diseases such as neurodegeneration, diabetes, and heart disease. To date, the regulatory mechanisms controlling the initiation, proliferation and termination of stem cell niches are still not fully understood. Here, we propose to determine the cellular and molecular basis underlying stem cell homeostasis using the Arabidopsis shoot apical meristem (SAM) as a model system. Because undifferentiated stem cells in Arabidopsis SAMs are at and near the surface and the living SAMs can maintain sessile during experiments, non-invasive time-lapse live imaging approaches are particularly effective in Arabidopsis, to follow the fate of each stem cell and their derivatives and to quantify cell dynamics in vivo. In addition, great genetic resources in Arabidopsis allow us to quantitatively dissect gene function through using an existing array of mutants with changed SAM sizes and stem cell numbers. Using this system, through a combination of in vivo time-lapse confocal imaging, transient and stable perturbations of gene function, in vitro biochemistry and in silico quantification and modeling approaches, we aim to uncover mechanisms by which a small group of key transcriptional regulators that are excluded from stem cells but determine the identity and activity of the stem cells in the SAMs. Our work will not only define the yet missing molecular linkage and cell-cell communication between differentiated and undifferentiated cells, but also elucidate a regulatory network underlying a cell non- autonomous phenomenon in control of stem cell homeostasis.