期刊
PLANT COMMUNICATIONS
卷 1, 期 1, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.xplc.2019.100002
关键词
Arabidopsis; ARGONAUTE1; ZWILLE (ARGONAUTE10); HD-ZIP III; stem cell; shoot meristem
资金
- Baden-Wurttemberg Stiftung
- German Research Foundation (DFG) under Germany's Excellence Strategy [CIBSS -EXC-2189, ID390939984]
- ERA-CAPS [La606/14, La606/17]
Pluripotent stem cells localized in proliferating growth centers, the meristems, are the origin of life-long organ formation and growth in higher plants. In the shoot apical meristem of Arabidopsis thaliana, the closely related ARGONAUTE proteins AGO1 and ZLL/AGO10 bind miR165/166 species to regulate mRNAs of HD-ZIP III transcription factors that are essential to maintaining stem cells. Several genetic studies showed that AGO1 and ZLL/AGO10 act redundantly to maintain stem cells. By contrast, the reported biochemical data suggested antagonistic functions: AGO1 utilizes miR165/166 to slice HD-ZIP III mRNAs, whereas ZLL/AGO10 promotes degradation of miR165/166 and thus stabilizes HD-ZIP III mRNAs. How these different functions are balanced in stem cell regulation has remained enigmatic. Here, we show that autorepression of AGO1 through miR168-mediated slicing of its own RNA is required to maintain the ability of AGO1 to suppress HD-ZIP III mRNAs. Increased AGO1 expression, either in the miR168a-2 mutant or by transgenic expression, inhibits this ability despite the presence of high levels of miR165/166, effectively uncoupling HD-ZIP III and miR165/166 expression. AGO1 activity can be restored, however, by increasing the levels of chaperones SQN and HSP90, which promote assembly of RNA-induced silencing complex (RISC). This suggests that cellular abundance of SQN and HSP chaperones limits AGO1-mediated RNA interference in shoot meristem stem cell regulation. Localized misexpression of AGO1 indicates that the cells surrounding the shoot meristem primordium play a crucial role in stem cell development. Taken together, our study provides a framework that reconciles biochemical and genetic data, showing that restriction of AGO1 levels by miR168-mediated autorepression is key to RISC homeostasis and the function of AGO1 in stem cell regulation.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据