Cell polarity, asymmetric cell division and differentiation in plants.

项目总结 从有限数量的祖细胞中产生不同的后代对多细胞来说是一个巨大的挑战 有机体。祖细胞在不断更新自己的同时产生新的细胞类型；这个过程 需要不对称细胞分裂(ACD)，这是干细胞的一个标志。ACD过程中的一个关键过程是细胞 祖细胞的极化。这项研究的长期目标是阐明 控制植物ACD中的细胞极化和细胞命运分化。 植物气孔的形成和形成需要ACDs的精确控制。拟南芥的气孔 系统为研究植物中ACD的机制提供了一个很好的平台，因为这些划分是 千篇一律和高度可预测的，叶表皮暴露在空气中很容易获得基因 鉴定和细胞检查。等电点分析鉴定了拟南芥中第一个内源性极性蛋白BASL (气孔谱系的断裂不对称)，它通过其在质膜上的高度极化分布来控制ACD 薄膜。然而，皮质BASL极性区域是如何定义的，以及细胞极性是如何调节气孔的 ACD在很大程度上仍然难以捉摸。拟议的研究将应用一种综合的方法，结合遗传学， 生物化学、高级细胞生物学和蛋白质组/磷蛋白质组学方法，以(1)了解水泡如何 运输控制靶向膜传递以促进气孔ACD细胞的极化和(2) 确定极性驱动的、不对称分布的内体活动如何区分 植物ACD。 研究中的分子机制包括蛋白质极化，膜内运输， 磷脂信号转导和细胞极化中信号转导与内体功能之间的串扰 和不对称细胞分裂，所有这些都明显与人类干细胞活性和 功能。

PROJECT SUMMARY Generating diverse progenies from a limited number of progenitor cells is a significant challenge for multicellular organisms. The progenitor cells continuously renew themselves while generating new cell types; this process requires asymmetric cell divisions (ACD), a hallmark of stem cells. A key process during ACD is the cellular polarization of progenitor cells. The long-term goal of the research is to elucidate the design principles that govern cellular polarization and cell fate differentiation in plant ACD. The formation and patterning of stomata in plants require precisely controlled ACDs. The Arabidopsis stomata system provides an excellent platform to study the mechanisms for ACD in plants, because these divisions are stereotypic and highly predictable, and the leaf epidermis exposed in the air is readily accessible to genetic characterization and cellular examination. The PI identified the first intrinsic polarity protein in Arabidopsis, BASL (Break Asymmetry of the Stomatal Lineages), that controls ACD by its highly polarized distribution at the plasma membrane. However, how the cortical BASL polarity domain is defined and how cell polarity regulates stomatal ACD remain largely elusive. The proposed studies will apply a comprehensive approach combining genetics, biochemistry, advanced cell biology, and proteomic/phosphoproteomic methods to (1) understand how vesicular trafficking controls targeted membrane delivery to promote the polarization of stomatal ACD cells and (2) determine how polarity-driven, asymmetrically distributed endosomal activity differentiates two daughter cells in plant ACD. The molecular mechanisms under investigation involve protein polarization, endomembrane trafficking, phospholipid signaling, and crosstalk between signal transduction and endosomal function in cell polarization and asymmetric cell division, all of which are clearly related to the studies of human stem cell activity and function.