Browsing by Author "Lusche, Elizabeth"
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Item ARGONAUTE10 promotes the degradation of miR165/6 through the SDN1 and SDN2 exonucleases in Arabidopsis(Public Library of Science (PLoS), 2017-02-23) Yu, Yu; Ji, Lijuan; Le, Brandon H.; Zhai, Jixian; Chen, Jiayi; Lusche, Elizabeth; Gao, Lei; Liu, Chunyan; Cao, Xiaofeng; Mo, Beixin; Ma, Jinbiao; Meyers, Blake C.; Chen, Xuemei; Yu Yu, Lijuan Ji, Brandon H. Le, Jixian Zhai, Jiayi Chen, Elizabeth Luscher, Lei Gao, Chunyan Liu, Xiaofeng Cao, Beixin Mo, Jinbiao Ma, Blake C. Meyers, Xuemei Chen; Zhai, Jixian; Meyers, Blake C.The degradation of small RNAs in plants and animals is associated with small RNA 30 truncation and 30 uridylation and thus relies on exonucleases and nucleotidyl transferases. ARGONAUTE (AGO) proteins associate with small RNAs in vivo and are essential for not only the activities but also the stability of small RNAs. AGO1 is the microRNA (miRNA) effector in Arabidopsis, and its closest homolog, AGO10, maintains stem cell homeostasis in meristems by sequestration of miR165/6, a conserved miRNA acting through AGO1. Here, we show that SMALL RNA DEGRADING NUCLEASES (SDNs) initiate miRNA degradation by acting on AGO1-bound miRNAs to cause their 30 truncation, and the truncated species are uridylated and degraded. We report that AGO10 reduces miR165/6 accumulation by enhancing its degradation by SDN1 and SDN2 in vivo. In vitro, AGO10-bound miR165/6 is more susceptible to SDN1-mediated 30 truncation than AGO1-bound miR165/ 6. Thus, AGO10 promotes the degradation of miR165/6, which is contrary to the stabilizing effect of AGO1. Our work identifies a class of exonucleases responsible for miRNA 30 truncation in vivo and uncovers a mechanism of specificity determination in miRNA turnover. This work, together with previous studies on AGO10, suggests that spatially regulated miRNA degradation underlies stem cell maintenance in plants.