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ARGONAUTE 6 bridges transposable element m RNA ‐derived si RNA s to the establishment of DNA methylation
Author(s) -
McCue Andrea D,
Panda Kaushik,
Nuthikattu Saivageethi,
Choudury Sarah G,
Thomas Erica N,
Slotkin R Keith
Publication year - 2014
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201489499
Subject(s) - biology , argonaute , chromatin , dna methylation , transposable element , rna , rna interference , transcription (linguistics) , microbiology and biotechnology , gene silencing , epigenetics , genetics , dna , gene expression , gene , genome , linguistics , philosophy
Transposable elements ( TE s) generate mutations and chromosomal instability when active. To repress TE activity, eukaryotic cells evolved mechanisms to both degrade TE mRNA s into small interfering RNA s (si RNA s) and modify TE chromatin to epigenetically inhibit transcription. Since the populations of small RNA s that participate in TE post‐transcriptional regulation differ from those that establish RNA ‐directed DNA methylation ( R d DM ), the mechanism through which transcriptionally active TE s transition from post‐transcriptional RNA i regulation to chromatin level control has remained unclear. We have identified the molecular mechanism of a plant pathway that functions to direct DNA methylation to transcriptionally active TE s. We demonstrated that 21–22 nucleotide (nt) si RNA degradation products from the RNA i of TE mRNA s are directly incorporated into the ARGONAUTE 6 ( AGO 6) protein and direct AGO 6 to TE chromatin to guide its function in R d DM . We find that this pathway functions in reproductive precursor cells to primarily target long centromeric high‐copy transcriptionally active TE s for R d DM prior to gametogenesis. This study provides a direct mechanism that bridges the gap between the post‐transcriptional regulation of TEs and the establishment of TE epigenetic silencing.