title: DRD1-Pol V-dependent self-silencing of an exogenous silencer restricts the non-cell autonomous silencing of an endogenous target gene.
abstract: In plants, the exogenous transgene transcribing inverted-repeat (exo-IR) sequences produces double-stranded RNAs that are processed by DCL4. The 21-nt small interfering RNAs generated function as mobile signals to trigger non-cell autonomous silencing of target endogenes in the neighboring 10-15 cells. The potential involvement of nuclear silencing pathway components in signal spreading or sensing in target cells is not clear. Here, we demonstrate that the exo-IR silencer (exo-Pdsi) is negatively autoregulated through methylation spreading, which acts in cis to reinforce the self-silencing of the silencer. Mutations affecting nuclear proteins DRD1 and Pol V (NRPE1 or NRPD2) relieved exo-Pdsi self-silencing, resulting in higher levels of Pdsi transcripts, which increased the non-cell autonomous silencing of endo-PDS. Our results suggest that in an experimental silencing pathway, methylation spreading on a silencer transgene may not have a direct endogenous plant counterpart when the protein-encoding gene is the target. DRD1-Pol V-dependent de novo methylation, by acting in cis to reinforce self-silencing of exo-IR, may play a role in restraining the inappropriate silencing of active protein-coding genes in plants.
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant gene research, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Li
authors.initials: L
authors.lastname: Dong
authors.forename: Meng
authors.initials: M
authors.lastname: Liu
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Fang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhao
authors.forename: Xiang-Feng
authors.initials: XF
authors.lastname: He
authors.forename: Xiao-Bao
authors.initials: XB
authors.lastname: Ying
authors.forename: Yi-Yue
authors.initials: YY
authors.lastname: Zhang
authors.forename: Qi
authors.initials: Q
authors.lastname: Xie
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
authors.forename: Hui-Shan
authors.initials: HS
authors.lastname: Guo
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D019175:DNA Methylation; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D009154:Mutation; D030821:Plants, Genetically Modified / Q000235:genetics; D012330:RNA, Double-Stranded / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D017423:Sequence Analysis, RNA
chemical_list: D029681:Arabidopsis Proteins; D012330:RNA, Double-Stranded; D018749:RNA, Plant; D034741:RNA, Small Interfering; C538841:RNA polymerase V, Arabidopsis; D012321:DNA-Directed RNA Polymerases; C504888:DRD1 protein, Arabidopsis