Dose-dependent AGO1-mediated inhibition of the miRNA165/166 pathway modulates stem cell maintenance in arabidopsis shoot apical meristem

Abstract: 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

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Plant Communications. - 1, 1 (2020) , 100002, ISSN: 2590-3462

Classification and Topics

• Classification: Biowissenschaften, Biologie

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2025
• Creator: Du, Fei ; Gong, Wen ; Boscá, Sonia ; Tucker, Matthew R. ; Vaucheret, Hervé ; Laux, Thomas

Further information

• DOI: 10.1016/j.xplc.2019.100002
• URN: urn:nbn:de:bsz:25-freidok-2594824
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:20 AM CEST