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Current Biology：拟南芥STM基因的自激活回路维持腋分生组织活性

已有 4229 次阅读 2020-4-10 08:02 |个人分类:每日摘要|系统分类:论文交流

A Self-Activation Loop Maintains Meristematic Cell Fate for Branching

First author: Xiuwei Cao; Affiliations: CAS Institute of Genetics and Developmental Biology (中科院遗传与发育生物学研究所): Beijing, China

Corresponding author: Yuling Jiao

In plants and animals, self-renewing stem cell populations play fundamental roles in many developmental contexts. Plants differ from most animals in their retained ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems. In seed plants, branching is achieved by stem-cell-containing axillary meristems, which are initiated from a leaf axil meristematic cell population originally detached from the shoot apical meristem. It remains unclear how the meristematic cell fate is maintained. Here, we show that ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1) maintains the meristem marker gene SHOOT MERISTEMLESS (STM) expression in the leaf axil to enable meristematic cell fate maintenance. Furthermore, ATH1 protein interacts with STM protein to form a STM self-activation loop. Genetic and biochemical data suggest that ATH1 anchors STM to activate STM as well as other axillary meristem regulatory genes. This auto-regulation allows the STM locus to remain epigenetically active. Taken together, our findings provide a striking example of a self-activation loop that maintains the flexibility required for stem cell niche re-establishment during organogenesis.

在动植物中，干细胞群的自我更新在许多的发育进程中扮演着至关重要的作用。与绝大多数动物不同的是，植物能够保持其起始新的生长和发育周期的能力，而这种能力依赖于侧生分生组织的建立和活性维持。在种子植物中，分枝是通过含有干细胞的腋分生组织所形成的，而后者是由最初来自于茎尖分生组织的叶腋具分生能力的细胞群所起始的。然而，目前对于具分生能力的细胞的命运是如何维持还不清楚。本文中，作者发现拟南芥叶腋处ATH1基因通过维持分生组织标记基因STM的表达，从而维持了叶腋分生细胞命运。此外，ATH1蛋白能够与STM蛋白发生互作，形成一个STM基因的自激活回路。遗传和生化数据显示ATH1能够锚定STM，以激活STM基因以及其它的腋分生组织调控基因。这种自调控使得STM位点能够维持表观遗传活性。综上，本文的发现揭示了一个自激活回路，作用于维持植物器官发生过程中干细胞龛重建立所需的具分生能力的细胞群。