Arabidopsis Serrate Coordinates Histone Methyltransferases ATXR5/6 and RNA Processing Factor RDR6 to Regulate Transposon Expression

Publication date: 18 June 2018
Source:Developmental Cell, Volume 45, Issue 6
Author(s): Zeyang Ma, Claudia Castillo-González, Zhiye Wang, Di Sun, Xiaomei Hu, Xuefeng Shen, Magdalena E. Potok, Xiuren Zhang
Serrate (SE) is a key component in RNA metabolism. Little is known about whether and how it can regulate epigenetic silencing. Here, we report histone methyltransferases ATXR5 and ATXR6 (ATXR5/6) as novel partners of SE. ATXR5/6 deposit histone 3 lysine 27 monomethylation (H3K27me1) to promote heterochromatin formation, repress transposable elements (TEs), and control genome stability in Arabidopsis. SE binds to ATXR5/6-regulated TE loci and promotes H3K27me1 accumulation in these regions. Furthermore, SE directly enhances ATXR5 enzymatic activity in vitro. Unexpectedly, se mutation suppresses the TE reactivation and DNA re-replication phenotypes in the atxr5 atxr6 mutant. The suppression of TE expression results from triggering RNA-dependent RNA polymerase 6 (RDR6)-dependent RNA silencing in the se atxr5 atxr6 mutant. We propose that SE facilitates ATXR5/6-mediated deposition of the H3K27me1 mark while inhibiting RDR6-mediated RNA silencing to protect TE transcripts. Hence, SE coordinates epigenetic silencing and RNA processing machineries to fine-tune the TE expression.

Graphical abstract

Teaser

Serrate is a key factor in RNA metabolism. Here, Ma et al. uncover its new roles in regulating TE expression: SE promotes ATXR5/6-mediated H3K27me1 mark to repress TE transcription while protecting TE transcripts from the RDR6 silencing activity. Thus, Serrate coordinates the TGS and PTGS machineries to fine-tune TE expression.


https://ift.tt/2tl8XZo